25.09   DICHANTHELIUM (Hitchc. & Chase) Gould
Robert W. Freckmann
Michel G. Lelong

Plants perennial; cespitose, sometimes rhizomatous, sometimes with hard, cormlike bases, often with basal winter rosettes of leaves having shortly ovate to lanceolate blades, these often sharply distinct from the blades of the cauline leaves. Culms 5-150 cm, herbaceous, hollow, usually erect or ascending, rarely sprawling, in the spring often spreading, sometimes decumbent in the fall, usually branching from the mid- or lower culm nodes in summer and fall; branches rebranching 1-4 times, terminating in small secondary panicles that are usually partly included in the sheaths. Cauline leaves 3-14, usually distinctly longer and narrower than the rosette blades; ligules of hairs, membranous, or membranous and ciliate, sometimes absent; pseudoligules of 1-5 mm hairs often present at the bases of the blades immediately behind the true ligules; blades usually distinctly longer and narrower than those of the basal rosette, cross sections with non-Kranz anatomy; photosynthesis C3. Inflorescences panicles, terminal on the culms and branches; sterile branches and bristles absent; disarticulation below the glumes. Primary panicles terminating the culms, developing April-June(July), sometimes also in late fall, usually at least partially chasmogamous, often with a lower seed set than the secondary panicles; secondary panicles terminating the branches, produced from (May)June to fall, usually partially or totally cleistogamous. Spikelets 0.8-5.2 mm, not subtended by bristles, dorsally compressed, surfaces unequally convex, apices unawned. Glume apices not or only slightly gaping at maturity; lower glumes 1/5-3/4 as long as the spikelets, 1-5-veined, truncate, acute, or acuminate; upper glumes slightly shorter than the spikelets or exceeding the upper florets by up to 1 mm, 5-11-veined, not saccate, apices rounded to attenuate. Lower florets sterile or staminate; lower lemmas similar to the upper glumes; lower paleas sometimes present, thin, shorter than the lower lemmas; upper florets bisexual, sessile, plump, usually apiculate to mucronate, sometimes minutely so, or subacute to (rarely) acute; upper lemmas striate, chartaceous-indurate, shiny, usually glabrous, margins involute; upper paleas striate; lodicules 2; anthers 3. Caryopses smooth; pericarp thin; endosperm hard; hila round or oval. x = 9. Name from the Greek di, twice and anth, flowering, a reference to the two flowering periods.

Dichanthelium is a genus of approximately 72 species, 34 of which are native to the Flora region. It is often included in Panicum sensu lato, the two taxa being similar in gross morphology. Recent molecular data reinforce the morphological arguments for recognizing Dichanthelium as a distinct genus.

When the branches of Dichanthelium develop, in late summer or fall, the culms acquire a very different aspect; comments about the fall phase refer to the appearance of the plant or its culms following this branching. Unless stated otherwise, descriptions and measurements refer to structures of the culms and primary panicles, not those of the branches and secondary panicles. Ligule measurements usually include the hairs of the pseudoligule, if present, because the two are often difficult to distinguish with less than 30 magnification.


SELECTED REFERENCES Allred, K.W. and F.W. Gould. 1978. Geographic variation in the Dichanthelium aciculare complex (Poaceae). Brittonia 30:497-504; Giussani, L.M., J.H. Cota-Sánchez, F.O. Zuloaga, and E.A. Kellogg. 2001. A molecular phylogeny of the grass subfamily Panicoideae (Poaceae) shows multiple origins of C4 photosynthesis. Amer. J. Bot. 88:1993-2001; Gould, F.W. and C.A. Clark. 1978. Dichanthelium (Poaceae) in the United States and Canada. Ann. Missouri Bot. Gard. 65:1088-1132; Hitchcock, A.S. 1951 [title page 1950]. Manual of the Grasses of the United States, ed. 2, rev. A. Chase. U.S.D.A. Miscellaneous Publication No. 200. U.S. Government Printing Office, Washington, D.C., U.S.A. 1051 pp.; Hitchcock, A.S. and A. Chase. 1910. The North American species of Panicum. Contr. U.S. Natl. Herb. 15:1-396; LeBlond, R.J. 2001. Taxonomy of the Dichotoma group of Dichanthelium (Poaceae). Sida 19:821-837; Zuloaga, F.O., R.P. Ellis, and O. Morrone. 1993. A Revision of Panicum subg. Dichanthelium sect. Dichanthelium (Poaceae: Panicoideae: Paniceae) in Mesoamerica, the West Indies, and South America. Ann. Missouri Bot. Gard. 80:119-190.

1
Basal leaf blades similar in shape to those of the lower cauline leaves, usually erect to ascending, clustered at the base, sometimes small or vestigial; culms branching from near the base in the fall, with 2-4 leaves, only the upper 2-4 internodes elongated (2)
Basal leaf blades usually well-differentiated from the cauline blades, ovate to lanceolate, spreading, forming a rosette, or basal blades absent; culms usually branching from the midculm nodes in the fall, with 3-14 leaves, usually all internodes elongated (7)
2
Blades soft, 3-12 mm wide, usually ciliate; upper blades less than 20 times as long as wide; fall phase with short panicle-bearing branches, without sterile shoots (sect. Strigosa) (3)
Blades stiff, 1-5 mm wide, not ciliate; most upper blades at least 20 times as long as wide; fall phase with basal panicles and sterile shoots (sect. Linearifolia) (4)
3
Leaf sheaths with retrorse or spreading hairs; upper blades 4-17 cm long, at least 3/4 as long as the basal blades; blade margins usually finely short ciliate, the cilia not papillose-based; spikelets with papillose-based hairs ..... 29. D. laxiflorum
Leaf sheaths glabrous or with ascending hairs; upper blades 1.5-6 cm long, less than 3/4 as long as the basal blades; blade margins with papillose-based cilia; spikelets glabrous or pubescent, hairs not papillose-based ..... 30. D. strigosum
4
Upper glumes and lower lemmas forming a beak extending 0.2-1 mm beyond the upper florets; spikelets 3.2-4.3 mm long; primary panicles with 7-25 spikelets ..... 34. D. depauperatum
Upper glumes and lower lemmas equaling or exceeding the upper florets by no more than 0.3 mm, not forming a beak; spikelets 2-3.4 mm long; primary panicles with 12-70 spikelets (5)
5
Cauline blades 4-8 cm long, all alike; basal blades ascending to spreading ..... 31 D. wilcoxianum
Uppermost cauline blades 10-20 cm long, distinctly longer than the lower blades; basal blades erect to ascending (6)
6
Panicles 1-3 cm wide, with ascending branches and appressed pedicels; spikelets turgid, 2.6-3.4 mm long, 1-1.7 mm wide, upper florets obovoid ..... 32. D. perlongum
Panicles 2-6 cm wide, with spreading branches and pedicels; spikelets not turgid, 2-3.2 mm long, 0 8-1.4 mm wide, upper florets ellipsoid ..... 33. D. linearifolium
7
Bases of the culms hard, cormlike; basal rosettes absent; spikelets with papillose-based hairs and attenuate basally (sect. Pedicellata) (8)
Bases of the culms not cormlike; basal rosettes usually present; spikelets not both with papillose-based hairs and attenuate basally (9)
8
Culms erect in the spring; cauline leaves 4-7, with thin, glabrous or sparsely hirsute blades that widen distal to the rounded to subcordate bases; lower glumes not encircling the pedicels, subadjacent to the upper glumes ..... 1. D. pedicellatum
Culms decumbent to ascending in the spring; cauline leaves 8-14, with thick, firm, puberulent blades that are parallel-sided distal to the rounded to truncate bases; lower glumes almost to completely encircling the pedicels, attached about 0.2 mm below the upper glumes ..... 2. D. nodatum
9
Blades cordate, thick, with white, cartilaginous margins; spikelets usually spherical to broadly obovoid or broadly ellipsoid, 1-1.8 mm long (sect. Sphaerocarpa) (10)
Blades not cordate or the spikelets not both spherical and less than 1.9 mm long; blade margins usually not white and cartilaginous (12)
10
Spikelets 1-1.4 mm long; lower glumes 0.2-0.4 mm long; cauline blades 5-10 mm wide ..... 23. D. erectifolium
Spikelets 1.3-1.8 mm long; lower glumes 0.4-0.8 mm long; cauline blades 5-25 mm wide (11)
11
Cauline blades 4-7, 10-25 cm long, 14-25 mm wide, with evident veins; culms nearly erect; panicles less than 1/2 as wide as long ..... 24. D. polyanthes
Cauline blades 3-4(6), 1.5-10 cm long, 5-14 mm wide, with obscure veins; culms decumbent or ascending; panicles more than 1/2 as wide as long ..... 25. D. sphaerocarpon
12
Lower glumes thinner and more weakly veined than the upper glumes, attached about 0.2 mm below the upper glumes, the bases clasping the pedicels; spikelets attenuate basally (13)
Lower glumes similar in texture and vein prominence to the upper glumes, attached immediately below the upper glumes, the bases not clasping the pedicels; spikelets usually not attenuate basally (15)
13
Blades 2-7 cm long, about 10 times as long as wide, not or slightly involute, spreading, without raised veins, not longitudinally wrinkled; spikelets obovoid-obpyriform, planoconvex in side view (sect. Lancearia) ..... 26. D. portoricense
Blades 4-16 cm long, more than 14 times as long as wide, or involute, stiffly erect or ascending, with prominently raised veins, the lower blades usually longitudinally wrinkled; spikelets ellipsoid to obovoid, biconvex in side view (sect. Angustifolia) (14)
14
Culms densely villous; nodes densely bearded; spikelets densely pubescent ..... 28. D. consanguineum
Culms glabrous, puberulent, or pilose with papillose-based hairs; nodes glabrous, puberulent to lightly bearded; spikelets glabrous or pubescent ..... 27. D. aciculare
15
Culms arising from rhizomes 3-5 mm thick, with (5)7-14 cauline blades; sheaths strongly hispid or viscid, mottled with pale spots, constricted at the top (sect. Clandestina) (16)
Culms arising from caudices or from rhizomes to 2 mm thick, with 3-7(9) cauline blades; sheaths not viscid, rarely hispid, not mottled with pale spots or constricted at the top (18)
16
Nodes densely bearded above a viscid glabrous ring, often swollen; blades densely soft pubescent ..... 10. D. scoparium
Nodes glabrous or sparsely pubescent, not swollen; blades glabrous or sparsely pubescent (17)
17
Cauline blades 7-15 mm wide, apices involute, long tapering; spikelets glabrous or sparsely puberulent ..... 8. D. scabriusculum
Cauline blades 15-30 mm wide, apices flat, acuminate; spikelets sparsely pubescent ..... 9. D. clandestinum
18
Ligules with a membranous base, ciliate distally; culms usually arising from slender rhizomes; lower florets often staminate; cauline blades 5-40 mm wide, often with a cordate base (sect. Macrocarpa) (19)
Ligules of hairs (except for D. nudicaule); culms arising from caudices; lower florets sterile; cauline blades 1-18 mm wide, bases usually tapered, rounded, or truncate at the base, sometimes cordate (23)
19
Spikelets ellipsoid, not turgid, with pointed apices; cauline blades 4-6, cordate at the base; sheaths without papillose-based hairs (20)
Spikelets obovoid, turgid, with rounded apices; cauline blades 3-4, tapered, rounded or truncate to cordate at the base; sheaths with papillose-based hairs (22)
20
Spikelets 2.2-3.2 mm long; ligules about 0.3 mm long; blades 5-25 mm wide; lower floret sterile ..... 5. D. commutatum
Spikelets 2.9-5.2 mm long; ligules 0.4-0.9 mm long; blades 15-40 mm wide; at least some lower florets staminate (21)
21
Nodes glabrous or slightly bearded; spikelets 2.9-3.9 mm long ..... 3. D. latifolium
Nodes densely retrorsely bearded; spikelets 3.8-5.2 mm long ..... 4. D. boscii
22
Blades and spikelets with papillose-based hairs; panicles usually slightly longer than wide, with spreading to ascending branches ..... 6. D. leibergii
Blades glabrous; spikelets puberulent to almost glabrous; panicles usually more than twice as long as wide, with nearly erect branches ..... 7. D. xanthophysum
23
Lower internodes short, upper nodes elongated; flag leaves distant and much reduced; culms rarely branching in the fall; branches, if present, few, developing from basal and subbasal nodes, erect (sect. Nudicaulia) ..... 19. D. nudicaule
Lower internodes about as long as the upper internodes; flag leaves usually not much reduced; culms branching in the fall; branches often many, developing from mid- or upper culm nodes, often spreading (24)
24
Spikelets 2.5-4.3 mm long, usually obovoid, turgid; upper glumes usually with an orange or purple spot at the base, the veins prominent (sect. Oligosantha) (25)
Spikelets 0.8-3 mm long, ellipsoid or obovoid, not turgid; upper glumes lacking an orange or purple spot at the base and the veins not prominent (27)
25
Nodes glabrous or sparsely pubescent; abaxial surfaces of the blades glabrous or pubescent, but not velvety pubescent ..... 11. D. oligosanthes
Nodes bearded with spreading to retrorse hairs; abaxial surfaces of the blades softly velvety pubescent (26)
26
Spikelets 3.7-4.3 mm long; culms 2-3 mm thick, stiffly erect; ligules 2-5 mm long, without pseudoligules; blades glabrous or sparsely pilose on the adaxial surfaces ..... 12. D. ravenelii
Spikelets 2.5-3.2 mm long; culms usually 1-2 mm thick, erect; ligules 0.5-1 mm long, with the adjacent pseudoligules 1-3 mm long; blades densely velvety pubescent on both surfaces ..... 13. D. malacophyllum
27
Ligules and adjacent pseudoligules 1-5 mm long, or the culms and sheaths with long hairs and also puberulent; spikelets variously pubescent to subglabrous (sect. Lanuginosa) (28)
Ligules absent or to 1.8 mm long, without adjacent pseudoligules; culms and at least the upper sheaths glabrous or sparsely pubescent with hairs of 1 length only; spikelets glabrous or pubescent (30)
28
Spikelets 0.8-1.1 mm long, puberulent to subglabrous; culms delicate, 0.3-0.8 mm thick ..... 16. D. wrightianum
Spikelets 1.1-3 mm long, variously pubescent; culms not delicate, usually more than 1 mm thick (29)
29
Spikelets 1.1-2.1 mm long; sheaths glabrous or pubescent with hairs no more than 3 mm long ..... 14. D. acuminatum
Spikelets 1.8-3 mm long; sheaths with hairs to 4 mm long ..... 15. D. ovale
30
Culms (18)40-100 cm tall, rarely delicate, usually more than 1 mm thick; spikelets 1.5-2.7 mm long; blades 3.5-14 cm long, 5-14 mm wide (sect. Dichanthelium) (31)
Culms 5-40(55) cm tall, delicate, usually less than 1 mm thick; spikelets 1.1-1.7 mm long; longest blades 1.5-6 cm long, 1.5-6 mm wide (sect. Ensifolia) (32)
31
Spikelets glabrous or, if pubescent, either the nodes bearded or the culms weak and prostrate; blade of the flag leaf usually spreading ..... 17. D. dichotomum
Spikelets pubescent; nodes glabrous; culms erect or ascending; blade of the flag leaf erect or ascending ..... 18. D. boreale
32
Culms reclining or weakly erect; cauline blades 4-9, usually without prominent white, cartilaginous margins; ligules often more than 1 mm long ..... 20. D. ensifolium
Culms erect, sometimes geniculate basally; cauline blades 3-5, with prominent white, cartilaginous margins; ligules 0.2-0.7 mm long (33)
33
Culms few per clump; the fall phase branching sparingly; cauline blades flat, the bases rounded; blades of the flag leaves much shorter than those of the lower leaves ..... 21. D. tenue
Culms many per clump; the fall phase branching extensively; cauline blades often involute, the bases subcordate; blades of the flag leaves only slightly shorter than those of the lower leaves ..... 22. D. chamaelonche


Dichanthelium sect. Pedicellata (Hitchc. & Chase) Freckmann & Lelong

Plants usually cespitose, sometimes with knotty rhizomes; basal rosettes absent. Culms initially erect, ultimately decumbent, often with hard, cormlike bases; fall phase freely divaricate-branching before the primary panicles mature. Cauline leaves 4-14; sheaths glabrous or pubescent, not viscid; ligules membranous and ciliate or of hairs; blades with papillose-based marginal cilia. Primary panicles exserted. Spikelets obovoid to obpyriform, with papillose-based hairs, attenuate basally. Upper florets with pointed to attenuate, puberulent apices.


1.   Dichanthelium pedicellatum (Vasey) Gould
Corm-Based Panicgrass

Plants cespitose, not rhizomatous. Basal rosettes absent. Culms 20-70 cm, initially erect, with hard, cormlike bases; nodes puberulent to sparsely hirsute; internodes all elongated, puberulent to hirsute; fall phase with decumbent culms, developing divaricate branches from the midculm nodes before the primary panicles mature. Cauline leaves 4-7; sheaths sometimes overlapping, puberulent to papillose-hispid, margins ciliate; ligules 0.3-1 mm, membranous and ciliate; blades 3-12 cm long, 2-8 mm wide, widening distal to the rounded or subcordate bases, thin, glabrous or sparsely hirsute, margins with papillose-based cilia. Primary panicles 3-6 cm long, 2-4 cm wide, exserted; branches spreading at maturity; pedicels somewhat divergent. Spikelets 3.2-4.4 mm long, 1.3-1.6 mm wide, narrowly obovoid-ellipsoid, papillose-hirsute, attenuate to the purplish bases. Lower glumes about 1/2 as long as the spikelets, narrowly triangular, subadjacent to the upper glumes, not encircling the pedicels; upper glumes about 0.3 mm shorter than the upper florets; lower florets sterile; upper florets with pointed, minutely puberulent apices. 2n = 18.

Dichanthelium pedicellatum grows on limestone outcroppings and in dry, open oak woodlands. Its range extends from Texas into Mexico and Guatemala. Primary panicles develop from late March into June (and sometimes from late August to November) and are open-pollinated; secondary panicles develop from May into fall and are at least partly cleistogamous.


2.   Dichanthelium nodatum (Hitchc. & Chase) Gould
Sarita Panicgrass

Plants usually cespitose, rarely rhizomatous. Basal rosettes absent. Culms 20-65 cm, decumbent to ascending even in spring, with hard, cormlike bases; nodes puberulent to sparsely pubescent; internodes scabrous-puberulent to papillose-hirsute; fall phase with geniculate to decumbent culms, developing divaricate branches from the midculm nodes before the primary panicles mature. Cauline leaves 8-14; sheaths not overlapping, puberulent to papillose-hirsute, margins ciliate; ligules 0.1-1 mm, of hairs; blades 3-9 cm long, 4-8 mm wide, thick, firm, puberulent, sides parallel above the rounded to truncate bases, margins with papillose-based cilia. Primary panicles 3-13 cm long, 2-8 cm wide, exserted; branches ascending to divaricate at maturity; pedicels appressed. Spikelets 3.4-4.4 mm long, 1.3-1.6 mm wide, narrowly obovoid-obpyriform, finely pubescent, hairs papillose-based, bases long, narrow. Lower glumes 1.5-2 mm, attached about 0.2 mm below the upper glumes, partly or completely encircling the pedicels; upper glumes about 0.3 mm shorter than the upper florets, purplish at the bases; lower florets sterile; upper florets with pointed, puberulent apices. 2n = 18 (J.K. Wipff, pers. com., 2001).

Dichanthelium nodatum grows in oak savannahs near the Gulf coast from Texas to northeastern Mexico. The primary panicles are produced from April into June (sometimes late August to November) and are at least partly open-pollinated; the secondary panicles are produced from May into fall and are at least partly cleistogamous.


Dichanthelium sect. Macrocarpa Freckmann & Lelong

Plants cespitose, often with knotty rhizomes,sometimes with caudices. Basal rosettes usually well-differentiated. Culms 20-110 cm, ascending to erect; fall phase sparsely rebranching, not producing dense axillary fascicles. Cauline leaves 3-6; sheaths glabrous or pubescent, not viscid; ligules shortly membranous and ciliate, cilia longer than the membranous portion. Primary panicles at least partially exserted. Spikelets narrowly ellipsoid to obovoid, pubescent to puberulent, sometimes sparsely so, hairs sometimes papillose-based. Upper florets pointed, umbonate, mucronate, or apiculate.


3.   Dichanthelium latifolium (L.) Harvill
Broadleaved Panicgrass, Panic à Larges Feuilles

Plants forming small clumps, with knotty rhizomes less than 2 mm thick. Basal rosettes well-differentiated; sheaths pubescent; blades ovate to lanceolate, dark green. Culms 45-110 cm, nearly erect; nodes glabrous or the lower nodes slightly bearded; internodes glabrous or sparsely pubescent; fall phase branching from the midculm nodes, branches nearly erect, scarcely rebranching, blades and secondary panicles only slightly reduced. Cauline leaves 4-6, often with a transitional leaf above the basal rosette; sheaths not overlapping, glabrous or softly villous basally, margins ciliate, collars pubescent; ligules 0.4-0.7 mm, membranous, ciliate, cilia longer than the membranous portion; blades 3.7-7 times longer than wide, 15-40 mm wide, ovate-lanceolate, glabrous or sparsely pubescent, with 11-13 major veins and 40-120 minor veins, bases cordate-clasping, with papillose-based cilia. Primary panicles 7-15 cm long, 4-12 cm wide, 1.5-2 times as long as wide, with 20-80 spikelets, eventually at least partially exserted; branches stiff, ascending to spreading. Spikelets 2.9-3.9 mm long, 1.6-2 mm wide, ellipsoid, sparsely pubescent. Lower glumes 1/3-1/2 as long as the spikelets, narrowly triangular; upper glumes and lower lemmas slightly shorter than the spikelets, often red-tinged basally and apically; lower florets staminate, anthers exserted prior to those of the upper florets; upper florets pointed, apiculate, upper lemmas with a minute fringe of hairs. 2n = 18, 36.

Dichanthelium latifolium grows in rich deciduous woods, often in slightly open areas within eastern North America. The primary panicles are open-pollinated and develop in May and June (and sometimes in September and October), the secondary panicles, which are producedfrom July through September, are rarely open-pollinated.


4.   Dichanthelium boscii (Poir.) Gould & C.A. Clark
Bosc's Panicgrass, Panic de Bosc

Plants forming small clumps, with knotty rhizomes less than 2 mm thick. Basal rosettes well-differentiated; sheaths pubescent; blades ovate to lanceolate, dark green. Culms 25-75 cm, initially erect, often sprawling in the fall, nodes densely retrorsely bearded; internodes glabrous, or pilose with papillose-based hairs; fall phase branching from the midculm nodes, branches nearly erect, sparsely rebranching, blades and secondary panicles only slightly reduced. Cauline leaves 4-6, often with a transitional leaf above the basal rosette; sheaths not overlapping, bases puberulent to retrorsely pilose, margins ciliate, collars pubescent; ligules 0.4-0.9 mm, membranous, ciliate, cilia longer than the membranous portion; blades 3-6 times longer than wide, 15-40 mm wide, ovate-lanceolate, glabrous, puberulent, or pilose, with 11-15 major veins and 40-120 minor veins, bases cordate, margins with papillose-based cilia. Panicles 4-12 cm long, 4-12 cm wide, about as long as wide when fully expanded, partially included to tardily exserted, with 16-60 spikelets. Spikelets 3.8-5.2 mm long, 1.7-2.2 mm wide, narrowly ellipsoid, pubescent or puberulent. Lower glumes 1/3-1/2 as long as the spikelets, narrowly triangular; upper glumes shorter than the spikelets; lower florets usually staminate; upper florets pointed, with a minute tuft of hairs. 2n = 18, 36.

Dichanthelium boscii usually grows in semi-open areas in dry oak-hickory woods of the eastern United States. The primary panicles are open-pollinated and are produced from late April through June (and sometimes again in the fall); the secondary panicles are partly open-pollinated, and are produced from July through September.


5.   Dichanthelium commutatum (Schult.) Gould
Variable Panicgrass

Plants cespitose, with caudices or with rhizomes up to 2 mm thick. Basal rosettes well-differentiated; blades 1-14 cm long, to 22 mm wide, ovate to lanceolate. Culms 20-75 cm, erect or decumbent to sprawling, often purplish; nodes and internodes glabrous or puberulent to pubescent; fall phase initially nearly erect, often sprawling eventually, branches initially erect and apparently dichotomous, later rebranching, blades and secondary panicles smaller than those of the culms. Cauline leaves 4-6; sheaths not overlapping, often glaucous, purplish, or olivaceous, glabrous or puberulent, margins usually ciliate; ligules about 0.3 mm, membranous, ciliate, cilia longer than the membranous portion, rarely with adjacent, about 12 mm hairs; blades 5-16 cm long, 5-25 mm wide, linear to ovate-lanceolate, glabrous or puberulent, with 9-13 major veins and 30-80 minor veins, bases cordate-clasping, often asymmetrical, with papillose-based marginal cilia. Panicles 5-12 cm long, 3-10 cm wide, open, exserted; branches flexuous. Spikelets 2.2-3.2 mm long, 1.1-1.3 mm wide, ellipsoid, yellowish-green or purplish, pubescent. Lower glumes 0.7-1.8 mm; upper glumes and lower lemmas equaling or slightly shorter than the spikelets; lower florets sterile; upper florets often minutely umbonate. 2n = 18.

Dichanthelium commutatum is fairly common in dry to wet, semi-open woodlands. Its range extends from the eastern United States to South America. The primary panicles are open-pollinated and are produced from April through June; the secondary panicles are primarily cleistogamous and are produced from June through fall.

The four subspecies are fairly distinct in some parts of their ranges, but subsp. commutatum intergrades with the other three where they occur together.

1
Culms densely crisp-puberulent; spikelets 2.2-2.7 mm long; cauline blades usually 5-8 cm long, 5-10 mm wide, thick, the bases symmetrical; rosette blades usually less than 3 cm long and to 6 mm wide ..... subsp. ashei
Culms usually glabrous or sparsely pubescent; spikelets 2.6-3.2 mm long; cauline blades usually more than 8 cm long and 10 mm wide, thin, bases sometimes asymmetrical; rosette blades large, some more than 4 cm long and 10 mm wide (2)
2
Cauline blades nearly linear, 5-14 mm wide, about 10 times as long as wide; spikelets 3-3.2 mm long; lower glumes about 1/2 as long as the spikelets ..... subsp. equilaterale
Cauline blades ovate-lanceolate, 6-25 mm wide, about 4-8 times as long as wide; spikelets 2.6-3.2 mm long; lower glumes about 1/4 as long as the spikelets (3)
3
Culms decumbent or sprawling, with loose caudices or rhizomes; blades strongly asymmetric-falcate, often glaucous; spikelets 2.9-3.2 mm long; lower lemmas pointed ..... subsp. joorii
Culms more or less erect, with caudices; blades almost symmetrical, green, sometimes glaucous; spikelets 2.6-2.9 mm long; lower lemmas rounded ..... subsp. commutatum


Dichanthelium commutatum subsp. ashei (T.G. Pearson ex Ashe) Freckmann & Lelong

Plants from small caudices. Culms slender, wiry, erect, densely crisp-puberulent. Basal blades usually shorter than 3 cm, to 6 mm wide. Cauline blades 5-8 cm long, 5-10 mm wide, linear-lanceolate, thick, often yellowish-green, bases symmetrical. Spikelets 2.2-2.7 mm. Lower glumes 1/5-1/4 the length of the spikelets; lower lemmas pointed.

Dichanthelium commutatum subsp. ashei grows in open woodlands. It sometimes resembles, and may hybridize with, D. dichotomum.


Dichanthelium commutatum (Schult.) Gould subsp. commutatum
Plants with caudices. Culms more or less erect, usually glabrous, sometimes sparsely pubescent or puberulent. Basal blades large, usually 8-14 cm long, 7-22 mm wide. Cauline blades 3.5-8 times as long as wide, 6-25 mm wide, thin, ovate-lanceolate, green, sometimes glaucous, bases almost symmetrical. Spikelets 2.6-2.9 mm. Lower glumes about 1/4 as long as the spikelets; lower lemmas rounded apically.

Dichanthelium commutatum subsp. commutatum grows in wet to dry woodlands. Its range extends to South America.


Dichanthelium commutatum subsp. equilaterale (Scribn.) Freckmann & Lelong

Plants from loose caudices. Culms stiffly erect, glabrous. Basal blades large, usually 8-14 cm long, 7-22 mm wide. Cauline blades 5-14 mm wide, about 10 times longer than wide, linear, thin, firm, spreading. Spikelets 3-3.2 mm; lower glumes 1.6-1.8 mm, about 1/2 as long as the spikelets.

Dichanthelium commutatum subsp. equilaterale grows in sandy pine and oak woodlands. Its range extends to southeastern Mexico and Nicaragua.


Dichanthelium commutatum subsp. joorii (Vasey) Freckmann & Lelong

Plants from loose caudices or with knotty or loose rhizomes. Culms decumbent or sprawling, glabrous, sometimes glaucous, sometimes purplish. Basal blades large, usually 8-14 cm long, 7-22 mm wide. Cauline blades 8-25 mm wide, 4-8 times longer than wide, thin, ovate-lanceolate, often glaucous, strongly asymmetric-falcate. Spikelets 2.9-3.2 mm. Lower glumes about 1/4 as long as the spikelets; lower lemmas pointed.

Dichanthelium commutatum subsp. joorii grows in wet woodlands and swamps. Its range extends into Mexico.


6.   Dichanthelium leibergii (Vasey) Freckmann
Leiberg's Panicgrass

Plants cespitose, with knotty rhizomes no more than 2 mm thick. Basal rosettes well-differentiated; blades few, small, ovate to lanceolate. Culms 24-80 cm, glabrous or puberulent; nodes sparsely spreading-pilose; internodes mostly elongated, glabrous or puberulent; fall phase with a few suberect branches from the lower and midculm nodes, blades slightly reduced, secondary panicles partially exserted. Cauline leaves 3-4; sheaths not overlapping, with ascending papillose-based hairs; ligules 0.3-0.5 mm, membranous, ciliate, cilia longer than the membranous portion; blades 5-15 cm long, 7-13 mm wide, ascending to erect, sparsely to densely pubescent with papillose-based hairs, with 9-11 prominent major veins and 25-50 minor veins, bases truncate to cordate, margins with papillose-based cilia. Panicles 6-10 cm long, 3-5 cm wide, their length usually less than twice their width, eventually well-exserted, with 20-40 spikelets; branches spreading to ascending. Spikelets 3.3-3.8 mm long, 1.6-2mm wide, ellipsoid-obovoid, turgid, pubescent, hairs papillose-based, apices rounded. Lower glumes about 1.8 mm, narrowly triangular; lower florets staminate; upper florets mucronate. 2n = 18.

Dichanthelium leibergii grows primarily on prairie relics, butis occasionally found in sandy woodlands. The primary panicles are produced from mid-May through July, the secondary panicles from late June to September. Sterile putative hybrids with D. acuminatum and D. xanthophysum are occasionally found.


7.   Dichanthelium xanthophysum (A. Gray) Freckmann
Pale Panicgrass, Panic Jaunâtre

Plants loosely cespitose, with knotty rhizomes to 2 mm thick. Basal rosettes often poorly differentiated; blades few, grading into the cauline blades. Culms 20-55 cm, most forming in the spring, additional culms sometimes produced in the fall; nodes glabrous or sparsely ascending-pubescent; internodes all elongated, glabrous or puberulent; fall phase with a few suberect branches from the lower and midculm nodes, branches not rebranching, blades slightly reduced, secondary panicles partially exserted. Cauline leaves 3-4; lower sheaths not overlapping, sometimes pubescent; upper sheaths overlapping, sparsely to densely pubescent, hairs papillose-based, margins ciliate; ligules 0.3-0.5 mm, membranous, ciliate, cilia longer than the membranous bases; blades 7-17 cm long, 7-23 mm wide, erect, pale yellow-green to bluish-green, glabrous, with 7-11 prominent major veins and 30-110 minor veins, bases tapered or rounded to truncate, margins with papillose-based cilia. Panicles 7-14 cm long, 1-5 cm wide, their length usually more than twice their width, narrowly cylindric, eventually well-exserted, with 9-46 spikelets; branches strongly ascending, stiff. Spikelets 3.2-4.1 mm long, 1.8-2.2 mm wide, obovoid, turgid, puberulent to subglabrous, with rounded apices. Lower glumes 1.7-2.2 mm, narrowly triangular; lower florets staminate; upper florets longer than the upper glumes, mucronate. 2n = 36.

Dichanthelium xanthophysum usually grows on sandy or rocky soils in semi-open pine, oak, or aspen woodlands. It extends from eastern Saskatchewan and northeast Montana to Quebec, New England, and West Virginia. Plants from Minnesota and western Quebec approach D. leibergii in having cauline blades narrower than 10 mm, and papillose-based hairs. Sterile putative hybrids with D. leibergii and D. boreale are rare; those with D. boreale have been called Panicum calliphyllum Ashe.


Dichanthelium sect. Clandestina Freckmann & Lelong

Plants cespitose, with rhizomes 3-5 mm thick. Basal rosettes well-differentiated; blades 9-25 cm, ovate-lanceolate. Culms 50-150 cm; fall phase branching from the mid- and upper culm nodes, branches rebranching, often forming dense axillary fascicles, secondary panicles enclosed in the sheaths. Cauline leaves 5-14; sheaths usually widest near midlength, narrowed to the summit, strongly papillose-hispid or softly pubescent and viscid, summits often mottled with white to yellowish blotches; ligules membranous or of hairs. Primary panicles exserted. Spikelets 2.2-3.6 mm, ellipsoid to ovoid, with prominent veins, pointed. Upper florets acute to acuminate, sometimes umbonate or apiculate, apices often with a minute tuft of hairs.


8.   Dichanthelium scabriusculum (Elliott) Gould & C.A. Clark
Tall-Swamp Panicgrass

Plants in large clumps, with rhizomes 3-5 mm thick. Basal rosettes well-differentiated; sheaths pubescent; blades lanceolate. Culms 70-150 cm, robust, purplish; nodes glabrous or puberulent; internodes scabridulous to almost glabrous; fall phase branching from the mid- and upper culm nodes, developing numerous, well-separated, dense fascicles of many reduced blades and hidden secondary panicles. Cauline leaves 6-14; sheaths not overlapping, narrowing above midlength, sparsely to densely papillose-hispid, tops mottled with pale spots, margins ciliate, collars puberulent; ligules 0.5-1.2 mm, membranous; blades 12-25 cm long, 7-15 mm wide, linear, stiff, ascending to spreading, glabrous or sparsely pubescent, bases subcordate to constricted, margins scabridulous, apices long tapering, involute. Primary panicles 10-21 cm long, 6-13 cm wide, eventually well-exserted, with many spikelets; rachises and branches usually glabrous and mottled. Spikelets 2.2-2.8 mm long, 1-1.2 mm wide, ovoid-ellipsoid, often purplish, glabrous, rarely sparsely puberulent. Lower glumes 0.5-1 mm, acute; upper glumes and lower florets exceeding the upper florets, prominently 7-9-veined; lower florets sterile; upper florets acute to acuminate, with a minute tuft of hairs at the apices. 2n = 18.

Dichanthelium scabriusculum usually grows in wet, sandy, open sites, including shores, stream banks, swamps, and bogs. It is restricted to the eastern United States. The primary panicles develop from May to July, the secondary panicles, which are usually concealed within the sheaths, from July through November. Panicum aculeatum Hitchc. & Chase refers to what appear to be sterile hybrids with Dichanthelium clandestinum or robust subspecies of D. dichotomum; and P. bennettense W.V. Br. to hybrids with D. aciculare.


9.   Dichanthelium clandestinum (L.) Gould
Deer-Tongue Grass, Panic Clandestin

Plants forming large clumps, with rhizomes 3-5 mm thick. Basal rosettes well-differentiated; sheaths pubescent; blades ovate to lanceolate. Culms 50-140 cm, stout, pilose with papillose-based hairs to subglabrous; fall phase branching from the mid- and upper culm nodes, with a few, nearly erect, elongate branches, sparsely rebranching, sheaths overlapping, concealing the secondary panicles; nodes not swollen, glabrous or sparsely pubescent. Cauline leaves 5-10; sheaths not overlapping, striate-ribbed, narrowing above midlength, hispid to sparsely hirsute, hairs sometimes papillose-based, summits mottled with pale spots, margins ciliate, collars puberulent; ligules 0.4-0.9 mm, membranous; blades 10-25 cm long, 15-30 mm wide, flat, lanceolate, often rigid, glabrous or sparsely pubescent, with 9-13 major veins and 40-80 minor veins, bases cordate, with papillose-based cilia, apices acuminate. Primary panicles 8-16 cm long, 4-12 mm wide, exserted, with many spikelets. Spikelets 2.4-3.6 mm long, 1.2-1.5 mm wide, narrowly ellipsoid, sparsely pubescent. Lower glumes 1/3-1/2 as long as the spikelets, narrowly triangular; upper glumes and lower florets slightly shorter than the spikelets, with 7 or 9 prominent veins; lower florets sterile; upper florets umbonate, apices with a minute tuft of hairs. 2n = 36.

Dichanthelium clandestinum usually grows in semi-open areas in damp or sandy woodlands, thickets, or on banks. It is restricted to the eastern part of the Flora region. The primary panicles are open-pollinated for a brief period, and produced from late May to early July; the secondary panicles, which are cleistogamous and usually concealed within the sheaths, are produced from July through September.

Panicum recognitum Fernald refers to rare sterile hybrids with Dichanthelium dichotomum and perhaps D. scoparium; Panicum aculeatum Hitchc. & Chase to putative sterile hybrids with D. scabriusculum or D. dichotomum.


10.   Dichanthelium scoparium (Lam.) Gould
Velvety Panicgrass

Plants in small clumps, with rhizomes 3-5 mm thick. Basal rosettes well-differentiated; blades sometimes more than 10 cm, lanceolate. Culms 50-150 cm, usually robust, erect; nodes often swollen, densely bearded with thin retrorse hairs above a constricted, glabrous, viscid ring; internodes grayish-purple, velvety-pubescent; fall phase branching from the mid- and upper culm nodes, with long, repeatedly forking and often recurving branches, ultimately with fascicles of reduced blades and included secondary panicles. Cauline leaves 7-11; sheaths not overlapping, narrowing distally, lustrous, bases sparsely to densely retrorsely villous, hairs papillose-based, summits purplish, with yellowish spots; collars densely villous; ligules 0.5-2 mm, of hairs; blades 9-20 cm long, 9-20 mm wide, thick, densely soft pubescent, bases rounded to subcordate, margins ciliate basally. Primary panicles 6-16 cm long, 5-12 cm wide, well-exserted, dense; rachises softly pubescent basally; branches often mottled with purplish viscid spots, glabrous. Spikelets 2.2-2.8 mm long, 1.3-1.5 mm wide, ovoid-ellipsoid, often purplish basally, prominently veined, margins and apices sparsely to densely pubescent, hairs papillose-based. Lower glumes 0.6-1.3 mm, subtruncate to acuminate; lower florets sterile; upper florets minutely apiculate. 2n = 18.

Dichanthelium scoparium grows in moist, sandy, open, often disturbed areas of the southeastern United States. It is also present in the West Indies. The primary panicles are open-pollinated, produced from May to early August; the secondary panicles are cleistogamous and are produced from July through October.

Panicum glutinoscabrum Fernald may represent rare putative hybrids of Dichanthelium scoparium with D. acuminatum, and P. mundum Fernald, rare hybrids with D. dichotomum.


Dichanthelium sect. Oligosantha (Hitchc.) Freckmann & Lelong

Plants usually cespitose, often with caudices, clumps sometimes with only 1 culm. Basal rosettes well-differentiated. Culms 20-75 cm, with papillose-based hairs; fall phase branching from the mid- and upper culm nodes. Cauline leaves 4-7; sheaths glabrous or hirsute, hairs sometimes papillose-based; ligules 0.5-5 mm, of hairs, these often joined at the base into a thickened ring. Spikelets 2.5-4.3 mm, ellipsoid to obovoid, turgid. Upper glumes usually with an orange or purplish spot at the base, with 7-9 prominent veins. Upper florets umbonate, sometimes minutely so.


11.   Dichanthelium oligosanthes (Schult.) Gould
Few-Flowered Panicgrass

Plants cespitose, with caudices. Basal rosettes well-differentiated; blades 2-6 cm, few, ovate to lanceolate. Culms 20-75 cm, geniculate basally, stiffly erect distally; nodes glabrous or sparsely pubescent; internodes often purplish, glabrous, puberulent, or papillose-hirsute; fall phase branching from the midculm nodes, branches initially ascending to erect, sometimes developing simultaneously with and overtopping the primary panicles, later rebranching to form short, bushy clumps of blades and small, included secondary panicles. Cauline leaves 5-7; sheaths not overlapping, glabrous, puberulent, or ascending papillose-hispid, margins ciliate, collars loose, puberulent; ligules 1-3 mm, of hairs; blades 5-12 cm long, 4-15 mm wide, flat or partly involute, glabrous or pubescent abaxially, with 7-9 major veins only slightly more prominent than the minor veins, bases ciliate, rounded to truncate, margins cartilaginous. Primary panicles 5-9 cm long, 3-6 cm wide, partly enclosed to long-exserted, with 6-60 spikelets; branches stiff or wiry, puberulent or scabridulous. Spikelets 2.7-4.2 mm long, 1.7-2.4 mm wide, ellipsoid to broadly obovoid, turgid, glabrous or sparsely pubescent. Lower glumes 1-1.6 mm, acute, similar in texture and vein prominence to the upper glumes; upper glumes strongly veined, often orange to purplish at the base; lower florets sterile; upper florets with minutely umbonate apices. 2n = 18.

Dichanthelium oligosanthes grown throughout the southern portion of the Flora region, and extends into northern Mexico. The primary panicles are briefly open-pollinated, then cleistogamous, from late May to early June; the secondary panicles, which are produced from June to November, are cleistogamous. The subspecies intergrade in areas of overlapping range, but they are usually distinct elsewhere.

Specimens of Dichanthelium oligosanthes that have few elongated internodes, but those elongated more than usual, are often mistaken for D. wilcoxianum. Unlike that species, however, they have turgid spikelets with an orange spot at the base of the lemma, indicating that they belong to D. oligosanthes. Such specimens seem to be most common among collections made in the southern and southwestern states during November, February, or March.

Sterile hybrids with Dichanthelium acuminatum have often been called Panicum scoparioides Ashe. Apparent hybrids with D. malacophyllum, D. ovale, and D. acuminatum subsp. columbianum are occasionally found.

1
Spikelets ellipsoid to oblong-obovoid, usually 3.4-4.2 mm long, 1.7-2 mm wide, usually sparsely pubescent; blades usually 4-9 mm wide, more than 10 times longer than wide, often partly involute; ligules 2-3 mm ..... subsp. oligosanthes
Spikelets broadly obovoid-ellipsoid, 2.7-3.5 mm long, 2-2.4 mm wide, usually glabrous; blades usually 6-15 mm wide, less than 10 times longer than wide, flat; ligules 1-1.5 mm long ..... subsp. scribnerianum


Dichanthelium oligosanthes (Schult.) Gould subsp. oligosanthes

Culms 40-75 cm; internodes usually puberulent and also pubescent to pilose or appressed-hispid. Cauline sheaths usually puberulent and also pubescent to pilose or appressed-hispid; ligules 2-3 mm; blades usually 4-9 mm wide, more than 10 times longer than wide, stiff, spreading, usually densely appressed-pubescent abaxially, often involute towards the long-acuminate apices. Primary panicles with a few stiff branches; pedicels mostly 5-15 mm. Spikelets usually 3.4-4.2 mm long, 1.7-2 mm wide, ellipsoid to oblong-obovoid, usually sparsely pubescent. Upper glumes often with a faint orange spot at the base.

Dichanthelium oligosanthes subsp. oligosanthes grows in dry, open, sandy, oak or pine woodlands. Its range extends from southern Ontario and New Hampshire to the Texas Gulf coast. It has not yet been reported from Mexico.


Dichanthelium oligosanthes subsp. scribnerianum (Nash) Freckmann & Lelong
Scribner's Panicgrass

Culms 20-50 cm; internodes often lustrous, glabrous or sparsely papillose-hispid (rarely puberulent). Cauline sheaths often lustrous, glabrous or sparsely papillose-hispid (rarely puberulent); ligules 1-1.5 mm; blades usually 6-15 mm wide, less than 10 times longer than wide, flat, ascending to spreading, glabrous or sparsely pubescent abaxially, acute. Primary panicles denser than in subsp. oligosanthes, branches more flexible; pedicels mostly shorter than 5 mm. Spikelets usually 2.7-3.5 mm long, 2-2.4 mm wide, broadly obovoid-ellipsoid, usually glabrous. Upper glumes with a prominent orange to purplish spot at the base.

Dichanthelium oligosanthes subsp. scribnerianum grows in sandy or clayey banks and prairies. Its range extends from southern British Columbia to the east coast of the United States, and south into northern Mexico. It is the most widespread of the two varieties.


12.   Dichanthelium ravenelii (Scribn. & Merr.) Gould
Ravenel's Panicgrass

Plants cespitose, with caudices. Basal rosettes well-differentiated; blades 3-8 cm, ovate to lanceolate. Culms 25-75 cm, 2-3 mm thick, erect, purplish; nodes densely bearded with spreading to retrorse hairs above a glabrous ring; internodes pilose or ascending hirsute, hairs papillose-based, also puberulent; fall phase with nearly erect culms, branching from the mid- and upper culm nodes; branches short, ascending, bushy, with several reduced, partly enclosed secondary panicles. Cauline leaves 4-6; sheaths not overlapping, papillose-hirsute and puberulent; collars densely pubescent; ligules 2-5 mm, of hairs; blades 8-17 cm long, 8-18 mm wide, lanceolate, stiff,thick, abaxial surfaces densely soft-pubescent, velvety, adaxial surfaces glabrous or sparsely pilose, with 9-11 major veins slightly more prominent than the minor veins, bases rounded or subcordate, margins with papillose-based cilia, apices acuminate. Primary panicles 5-11 cm, almost as wide as long, shortly exserted, with few spikelets; rachises and branches scabridulous and finely pubescent, hairs papillose-based. Spikelets 3.7-4.3 mm long, 1.6-2.1 mm wide, obovoid, turgid, often shiny, sparsely pustulose-villous. Lower glumes 1.8-2.5 mm, loose, strongly veined, acute; upper glumes shorter than the spikelets, strongly veined, purplish at the base; lower florets sterile; upper florets with a minute tuft of hairs around the umbonate apices. 2n = 18.

Dichanthelium ravenelii grows in dry, sandy woodlands of the southeastern United States. The primary panicles develop from early May through June, and are at least partly open-pollinated. The secondary panicles, which are produced from July through September, are cleistogamous. Putative hybrids with other species are very rare.


13.   Dichanthelium malacophyllum (Nash) Gould
Soft-Leaved Panicgrass

Plants cespitose, with caudices. Basal rosettes well-differentiated; blades 2-4 cm, ovate to lanceolate. Culms 20-70 cm, usually 1-2 mm thick, erect; nodes retrorsely bearded; internodes puberulent and densely pubescent with soft, spreading to retrorse hairs, hairs papillose-based, papillae small; fall phase branching from the mid- and upper culm nodes, ultimately much rebranched, with short, bushy clumps of blades and small, included secondary panicles, this branching beginning before the primary panicles are exserted. Cauline leaves 5-6; sheaths not overlapping, pubescence not as dense as on the culms; collars puberulent; ligules 0.5-1 mm, of hairs, bases of the hairs forming a thickened ring, pseudoligules of 1-3 mm hairs also present; blades 5-10 cm long, 6-12 mm wide, lax, both surfaces velvety pubescent, with 9 or 11 major veins, these only slightly more prominent than the minor veins, bases rounded, margins ciliate. Primary panicles 3-7 cm long, 2-5 cm wide, tardily and shortly exserted; rachises and branches densely pubescent. Spikelets 2.5-3.2 mm long, 1.5-1.6 mm wide, broadly ellipsoid-obovoid, turgid, with papillose-based hairs, sometimes pilose. Lower glumes 1-1.6 mm, strongly veined, acute; upper glumes strongly veined, often purplish, especially towards the bases; lower florets sterile; upper florets minutely umbonate. 2n = 18.

Dichanthelium malacophyllum usually grows in cedar glades, on dry limestone soils. It is restricted to the United States. The primarypanicles are briefly open-pollinated from late May to early June; the secondary panicles, which are produced from June to November, are cleistogamous. The species occasionally intergrades, and perhaps hybridizes, with D. oligosanthes and D. acuminatum.


Dichanthelium sect. Lanuginosa (Hitchc.) Freckmann & Lelong

Plants cespitose, with caudices. Basal rosettes well-differentiated. Culms 15-100 cm, erect, ascending, or decumbent; internodes glabrous, puberulent, pilose, or densely pubescent or velvety; fall phase often much branched. Cauline leaves 4-7; sheaths glabrous, puberulent, sparsely to densely pubescent, pilose or velvety, often with hairs of two lengths; ligules 0.5-3 mm, of hairs, often with an adjacent pseudoligule of 2-5 mm hairs. Spikelets 0.8-3 mm, more or less ellipsoid, pubescent to subglabrous, acute to acuminate, upper glumes and lower lemmas not strongly veined. Upper florets acute to obtuse, sometimes minutely umbonate or apiculate.

Hybridization, often followed by segregation in autogamous lines, produces a reticulate pattern of intergradation between members of this section. In the descriptions, no distinction is made between the ligules and pseudoligules because of the difficulty of distinguishing the two at less than 30.


14.   Dichanthelium acuminatum (Sw.) Gould & C.A. Clark
Hairy Panicgrass, Panic Laineux

Plants more or less densely cespitose. Basal rosettes usually well-differentiated; blades ovate to lanceolate. Culms 15-100 cm (rarely taller), usually thicker than 1 mm, weak and wiry or relatively stout and rigid, erect, ascending or decumbent; nodes occasionally swollen, glabrous or densely pubescent, often with a glabrous or viscid ring below; internodes purplish or olive green or grayish-green, to yellowish-green, variously pubescent, with hairs of 2 lengths or glabrous; fall phase erect, spreading, or decumbent, usually branching extensively at all but the uppermost nodes, ultimately forming dense fascicles of branchlets with reduced, flat or involute blades and reduced secondary panicles with few spikelets. Cauline leaves 4-7; sheaths usually shorter than the internodes, glabrous or densely and variously pubescent with hairs shorter than 3 mm, margins ciliate or glabrous; ligules and pseudoligules 1-5 mm, of hairs; blades 2-12 cm long (rarely longer), 2-12 mm wide (rarely wider), firm or lax, spreading to reflexed or stiffly ascending, yellowish-green or grayish-green to olivaceous, densely to sparsely and variously pubescent, margins similar or occasionally whitish-scabridulous, margins often with papillose-based cilia, at least basally, bases rounded or subcordate. Primary panicles 3-12 cm, 1/4-3/4 as wide as long, usually open, well-exserted, rather dense; rachises glabrous, puberulent, or more or less densely pilose, at least basally. Spikelets 1.1-2.1 mm, obovoid to ellipsoid, yellowish-green to olivaceous or purplish, variously pubescent, obtuse or subacute. Lower glumes usually 1/4-1/2 as long as the spikelets, obtuse to acute; upper glumes and lower lemmas subequal, equaling the upper florets at maturity, or occasionally the upper glumes slightly shorter, not strongly veined; lower florets sterile; upper florets 1.1-1.7 mm long, 0.6-1 mm wide, ellipsoid, obtuse to acute or minutely umbonate or apiculate. 2n = 18.

Dichanthelium acuminatum is common and ubiquitous in dry to wet, open, sandy or clayey woods, clearings, bogs, and swamps, or in saline soil near hot springs, growing in much of the Flora region and extending into northern South America. It is probably the most polymorphic and troublesome species in the genus. The treatment presented here attempts to delimit the major variants present, but does not fully reflect the intricate reticulate pattern of morphological variation that exists. There is considerable overlap among the nine subspecies recognized and, in addition, there appears to be widespread introgression from other Dichanthelium species, such as D. dichotomum, D. sphaerocarpon, D. ovale, and D. aciculare into the D. acuminatum complex, contributing to the taxonomic difficulties.

1
Lower portion of the culms and lower sheaths usually glabrous or sparsely pubescent (2)
Lower portion of the culms and lower sheaths densely and variously pubescent or puberulent (4)
2
Primary panicles congested, more than twice as long as wide; spikelets ascending to appressed ..... subsp. spretum
Primary panicles open, less than twice as long as wide; spikelets diverging to ascending (3)
3
Blades green or purplish, the margins not conspicuously ciliate at the base; spikelets 1.1-1.5 mm long, usually ellipsoid ..... subsp. longiligulatum
Blades often yellowish-green, the margins usually with long, papillose-based cilia at the base; spikelets 1.3-1.6 mm long, usually obovoid ..... subsp. lindheimeri
4
Culms 15-30 cm tall; midculm sheaths nearly as long as the internodes; blades usually 2-6.5 cm long, less than 8 times longer than wide ..... subsp. sericeum
Culms usually 30-100 cm tall; midculm sheaths about 1/2 as long as the internodes; blades usually 6-12 cm long, more than 8 times longer than wide (5)
5
Culms and lower sheaths densely covered with spreading, villous hairs or soft, thin, papillose-based hairs, often with shorter hairs underneath; blades softly pubescent to velvety on the abaxial surfaces (6)
Culms and sheaths pilose with papillose-based hairs to hispid, with mostly ascending hairs, or densely puberulent with a few longer, ascending hairs also present; blades appressed-pubescent or puberulent abaxially, not velvety to the touch (7)
6
Primary panicles usually poorly exserted, on peduncles less than 6 cm long; blades suberect, the margins lacking cilia on the distal 1/2 ..... subsp. thermale
Primary panicles usually well-exserted, on peduncles more than 8 cm long; blades ascending to spreading, the margins ciliate along most of their length ..... subsp. acuminatum
7
Sheaths and culms densely puberulent, scattered long hairs often present also ..... subsp. columbianum
Sheaths and culms pilose with papillose-based hairs, the hairs mostly ascending, occasionally with inconspicuous, shorter hairs underneath (8)
8
Blades usually 6-12 mm wide, spreading to ascending, the adaxial surfaces nearly glabrous or with hairs shorter than 3 mm long; spikelets 1.5-2 mm ..... subsp. fasciculatum
Blades usually 2-6 mm wide, erect to ascending, spreading or reflexed, the adaxial surfaces glabrous or with hairs 3-6 mm long; spikelets 1.1-1.6 mm long (9)
9
Blades erect to ascending, the adaxial surfaces long-pilose; spikelets 1.3-1.6 mm long, usually broadly obovoid ..... subsp. implicatum
Blades ascending, spreading, or reflexed, the adaxial surfaces glabrous or sparsely pubescent; spikelets 1.1-1.5 mm long, usually ellipsoid ..... subsp. leucothrix


Dichanthelium acuminatum (Sw.) Gould & C.A. Clark subsp. acuminatum
Panic Laineux

Plants grayish olive green, densely velvety-villous throughout. Cauline nodes densely villous, with a glabrous ring below; fall phase branching extensively from the midculm nodes, forming conspicuous flabellate fascicles of branches. Cauline sheaths densely soft spreading-villous, often with inconspicuous smaller hairs underneath; midculm sheaths about 1/2 as long as the internodes; blades 6-12 cm long, to 10 mm wide, ascending to often spreading and slightly incurved, softly pubescent on both surfaces, with papillose-based cilia for most of their length. Primary panicles usually well-exserted, on peduncles longer than 8 cm. Spikelets 1.6-1.9 mm, broadly ellipsoid or obovoid.

Dichanthelium acuminatum subsp. acuminatum grows primarily in moist, open, sandy areas on the Atlantic and Gulf coastal plains. Its range extends through Mexico, the West Indies, and Central America to northern South America.


Dichanthelium acuminatum subsp. columbianum (Scribn.) Freckmann & Lelong
Panic du District de Columbia

Plants cespitose, pale bluish- or grayish-green. Culms erect to ascending, densely puberulent, longer hairs often present also, at least on the lower portion of the culms; nodes puberulent; fall phase with spreading or decumbent culms, branching early from most nodes, secondary blades not as greatly reduced or as densely crowded as in subsp. acuminatum, subsp. fasciculatum, subsp. implicatum, and subsp. leucothrix. Cauline sheaths pubescent, their pubescence similar to that of the culms but somewhat less dense; midculm sheaths about 1/2 as long as the internodes; ligules 1-1.5 mm; blades 3-7 cm long, 3-7 mm wide, relatively firm, often ascending, abaxial surfaces densely puberulent to nearly glabrous, adaxial surfaces glabrous or sparsely pilose near the base, margins whitish-scabridulous. Spikelets 1.5-1.9 mm, broadly ellipsoid or obovoid, puberulent.

Dichanthelium acuminatum subsp. columbianum grows in sandy woods or clearings. It is much less common than the other eastern subspecies of D. acuminatum. Occasionally, it resembles the more widespread subsp. fasciculatum, subsp. implicatum, and subsp. lindheimeri.

The culms and sheaths of Dichanthelium acuminatum subsp. columbianum are always puberulent with very short hairs. This puberulence should not be confused with the slightly longer hairs that develop on the secondary branches of other taxa.


Dichanthelium acuminatum subsp. fasciculatum (Torr.) Freckmann & Lelong
Panic Laineux

Plants yellowish-green to olivaceous or purplish. Culms 15-75 cm, suberect, ascending or spreading; nodes often with spreading hairs, occasionally with a glabrous ring below. Cauline sheaths with ascending to spreading, papillose-based hairs, occasionally with shorter hairs underneath; midculm sheaths about 1/2 as long as the internodes; blades 5-12 cm long, 6-12 mm wide, spreading to ascending, bases with papillose-based cilia, abaxial surfaces usually pubescent, adaxial surfaces pilose or glabrous, hairs shorter than 3 mm. Spikelets 1.5-2 mm (tending to be longer in the western part of its range), obovoid to ellipsoid.

Dichanthelium acuminatum subsp. fasciculatum grows primarily in disturbed areas, open or cut-over woods, thickets, and grasslands, in dry to moist soils, including river banks, lake margins, and marshy areas. It is widespread in temperate North America, growing from Canada to Mexico, but it is somewhat less common in the western part of its range, where it often occurs on moister areas.

Dichanthelium acuminatum subsp. fasciculatum includes probably the most widespread, ubiquitous, and variable assemblages of forms in the species. It is not always clearly separable from the other subspecies of D. acuminatum, especially subsp. acuminatum, subsp. implicatum, and subsp. lindheimeri. Gene exchange with other Dichanthelium species (including D. dichotomum, D. laxiflorum, D. ovale, D. commutatum, and D. boreale) probably occurs not infrequently.


Dichanthelium acuminatum subsp. implicatum (Scribn.) Freckmann & Lelong

Plants densely cespitose. Culms seldom over50 cm, slender, suberect, ascending or spreading; nodes more or less densely pubescent; fall phase branching extensively from the lower and midculm nodes, with conspicuous, flabellate fascicles of branches and reduced blades. Cauline sheaths shorter than the internodes, lower sheaths usually pilose with papillose-based hairs, upper sheaths often short-pubescent; midculm sheaths about 1/2 as long as the internodes; blades usually 2-6 mm wide, more than 8 times longer than wide, relatively firm, erect to ascending, often yellowish-green, abaxial surfaces densely pubescent with short papillose-based hairs or short-pubescent with subappressed hairs, adaxial surfaces more or less densely pilose, hairs to 6 mm, conspicuous, erect or ascending, occasionally with shorter hairs underneath. Spikelets 1.3-1.6 mm, usually broadly obovoid.

Dichanthelium acuminatum subsp. implicatum usually grows in low, moist areas, including open woodlands, meadows, bogs, and cedar and hemlock swamps, and also in drier, sandy areas. Its range extends from south central Canada to the midwestern and northeastern United States. It intergrades occasionally with the more widespread subsp. fasciculatum.


Dichanthelium acuminatum subsp. leucothrix (Nash) Freckmann & Lelong

Plants cespitose, pale olive green, often purplish-tinged. Culms usually 30-100 cm, erect to ascending, sparsely pubescent to almost glabrous, hairs appressed, thin, silvery, papillose-based; nodes sparsely pubescent; fall phase branching extensively from the lower and midculm nodes, with conspicuous, flabellate fascicles of branches and reduced blades. Cauline sheaths shorter than the internodes, sparsely pilose to nearly glabrous, hairs papillose-based, occasionally with shorter soft hairs underneath, margins ciliate; midculm sheaths about 1/2 as long as the internodes; blades usually 2-7 cm long, 2-7 mm wide, relatively firm, ascending, spreading, or reflexed, abaxial surfaces densely and softly puberulent, adaxial surfaces glabrous or sparsely appressed-villous, sometimes with a few longer hairs intermixed. Primary panicles open, long-exserted, dense. Spikelets 1.1-1.5 mm, usually ellipsoid, densely short-pubescent.

Dichanthelium acuminatum subsp. leucothrix grows in low, sandy or peaty pine savannahs of the coastal plain. Its range extends through Mexico, the West Indies, and Central America to northern South America. It is closely related, and often sympatric with, the more common, glabrous subsp. longiligulatum.


Dichanthelium acuminatum subsp. lindheimeri (Nash) Freckmann & Lelong

Culms often yellowish-green, usually glabrous; nodes glabrous; fall phase usually with stiffly spreading culms with dense fascicles of branches with reduced, often involute blades. Cauline sheaths often yellowish-green, usually glabrous or the lowest sheaths sparsely ascending-pubescent; blades 4-9 cm long, 4-8 mm wide, stiffly ascending or spreading, often yellowish-green, glabrous on both surfaces or puberulent abaxially, bases rounded, margins faintly whitish-scabridulous, with conspicuous, long, papillose-based cilia at the base. Primary panicles 3.5-7 cm, open, less than twice as long as wide. Spikelets 1.3-1.6 mm, diverging to ascending, usually obovoid, obtuse.

Dichanthelium acuminatum subsp. lindheimeri grows in dry or moist, sandy or clayey, open, often disturbed areas, open woodlands, limestone glades, and roadsides, primarily in the eastern portion of the species range. It intergrades occasionally with the pubescent subsp. fasciculatum and subsp. implicatum.


Dichanthelium acuminatum subsp. longiligulatum (Nash) Freckmann & Lelong

Very similar to subsp. spretum vegetatively. Fall phase branching profusely from the lower and midculm nodes, producing dense fascicles of reduced branches, blades, and secondary panicles. Cauline blades green or purplish. Primary panicles 3-8 cm, to 3/4 as wide as long, normally expanded; branches numerous, slender, ascending, spikelets densely packed. Spikelets 1.1-1.5 mm, usually ellipsoid, puberulent.

Dichanthelium acuminatum subsp. longiligulatum is common, especially in moist pine savannahs and bogs of the coastal plain; it also grows inland to Tennessee, and in Mexico, the West Indies, Central America, and South America. It is similar to subsp. leucothrix, which grows in the same habitat, often at the same sites.


Dichanthelium acuminatum subsp. sericeum (Schmoll) Freckmann & Lelong

Plants more or less densely cespitose. Culms usually less than 30 cm, stiffly ascending to spreading, densely pubescent. Midculm sheaths nearly as long as the internodes; midculm blades usually 2-6.5 cm, usually less than 8 times as long as wide. Primary panicles usually well-exserted. Spikelets mostly 1.6-1.8 mm.

Dichanthelium acuminatum subsp. sericeum grows in warm or hot ground around geysers and hot springs in the Rocky Mountains from Banff, Alberta south to Yellowstone National Park and east to Bighorn County, Wyoming.


Dichanthelium acuminatum subsp. spretum (Schult.) Freckmann & Lelong

Culms usually glabrous; nodes often swollen, glabrous; fall phase often with reclining culms, ultimately with fascicles of branches with greatly reduced blades and secondary panicles. Cauline sheaths usually glabrous; blades 3-9 mm wide, usually firm, ascending to reflexed, puberulent or glabrous abaxially, glabrous adaxially, with sparse papillose-based cilia at the bases. Primary panicles 4-12 cm long, 1/4-1/2 as wide as long, usually narrow, congested. Spikelets 1.3-1.9 mm, ascending to appressed, usually ellipsoid, usually puberulent (rarely glabrous).

Dichanthelium acuminatum subsp. spretum grows in wet to moist, sandy or peaty soil, pine savannahs, and bogs. It is not a common taxon, but is most frequent on the coastal plain and around the Great Lakes. It is very similar to the more common, southern subsp. longiligulatum. It also resembles D. dichotomum in size and overall habit.


Dichanthelium acuminatum subsp. thermale (Bol.) Freckmann & Lelong
Geyser Panicgrass

Plants often densely cespitose, densely and softly pubescent throughout, with soft, thin, spreading, papillose-based hairs on the culms and lower sheaths. Culms usually over 30 cm. Midculm sheaths about 1/2 as long as the internodes; blades at midculm generally 6.5-12 cm long, usually more than 7 times as long as wide, suberect, softly pubescent on the abaxial surface, without papillose-based cilia on the distal 1/2. Primary panicles usually poorly exserted, peduncles shorter than 6 cm. Spikelets mostly 1.8-2 mm.

Dichanthelium acuminatum subsp. thermale grows on the mineralized crust of warm, moist soil at the Geysers, Sonoma County, California; it is listed as endangered in that state.


15.   Dichanthelium ovale (Elliott) Gould & C.A. Clark
Stiff-Leaved Panicgrass

Plants cespitose. Basal rosettes well-differentiated; blades 1-8 cm, lanceolate, often conspicuously ciliate. Culms 15-60 cm, usually more than 1 mm thick, not delicate, mostly ascending or spreading, often decumbent; nodes densely to sparsely bearded with spreading, retrorse, or appressed hairs; internodes, particularly the lower internodes, usually long-hairy with appressed or ascending hairs, occasionally with spreading hairs, occasionally with shorter hairs, rarely nearly glabrous; fall phase with decumbent to prostrate culms, branching developing early and forming dense fascicles with erect, slightly reduced blades and greatly reduced secondary panicles. Cauline leaves 4-7; sheaths shorter than the internodes, pilose, hairs to 4 mm, occasionally with shorter, spreading hairs underneath; ligules and pseudoligules 1-5 mm, of hairs; blades 4-10 cm long, 3-10 mm wide, relatively firm, mostly ascending or spreading, 1 or both surfaces sparsely to densely pubescent with appressed or erect hairs, hairs to 5 mm, bases rounded or slightly narrowed, margins often whitish, ciliate basally, scabridulous elsewhere. Primary panicles 3-10 cm long, nearly as wide when fully expanded; rachises and branches often stiffly ascending or spreading, usually pilose basally. Spikelets 1.8-3 mm, ellipsoid or obovoid, densely to sparsely pilose or papillose-pilose, obtuse or slightly acute. Lower glumes 1/3-1/2 as long as the spikelets, often triangular, not strongly veined, usually acute or subacute; upper glumes usually slightly shorter than the lower lemmas and upper florets at maturity, not strongly veined; lower florets sterile; upper florets 1.6-2.5 mm, ellipsoid (slightly less than 1/2 as wide as long, or wider in subsp. praecocius), subacute. 2n = 18.

Dichanthelium ovale grows in dry, open, sandy or rocky woodland borders, sand barrens, dunes, and dry prairies in southeastern Canada, the eastern United States, the West Indies, Mexico, and Central America. The four subspecies often intergrade, especially subsp. villosissimum and subsp. pseudopubescens in the southeastern United States, and subsp. villosissimum and subsp. praecocius in the western part of their range.

The growth form and certain morphological features of Dichanthelium ovale resemble those of the widespread D. laxiflorum, which usually grows in more mesic habitats. Occasional specimens exhibit traits of D. acuminatum, D. oligosanthes, and D. commutatum.

1
Lower sheaths and lower culm internodes with soft, spreading or retrorse, papillose-based hairs, the longer hairs often longer than 4 mm long; spikelets 1.8-2.5 mm long (2)
Lower sheaths and lower culm internodes with ascending or appressed, non-papillose-based hairs shorter than 4 mm or nearly glabrous; spikelets 2.1-3 mm long (3)
2
Spikelets 2.1-2.5 mm long; culms usually more than 1 mm thick, stiff; largest blades usually 6-10 mm wide ..... subsp. villosissimum
Spikelets 1.8-2.1 mm long; culms usually less than 1 mm thick, wiry; largest blades usually 2-6 mm wide ..... subsp. praecocius
3
Spikelets 2.5-3 mm long; basal blades with long hairs on or near the margins and bases ..... subsp. ovale
Spikelets 2.1-2.6 mm long; basal blades usually without long hairs on or near the margins and bases ..... subsp. pseudopubescens


Dichanthelium ovale (Elliott) Gould & C.A. Clark subsp. ovale

Basal blades 3-8 cm, rigid, with long hairs on or near the bases and margins. Culms more than 1 mm thick, stiff; lower internodes pilose; upper internodes short-pilose to nearly glabrous. Cauline sheaths with ascending hairs, hairs to 4 mm, not papillose-based: ligules 1-4 mm; blades 5-12 mm wide, firm, ascending, abaxial surfaces appressed-pubescent, adaxial surfaces nearly glabrous except for the long hairs on or near the scabridulous margins and bases. Spikelets 2.5-3 mm, ellipsoid, sparsely to densely pilose. 2n = 18.

Dichanthelium ovale subsp. ovale grows in dry, open, sandy woods, pinelands, and sandhills along the east coast of the United States from New Jersey southwards, extending into the coastal plain from eastern Texas to South Carolina, and in Mexico, Honduras, Guatemala, and Nicaragua. It intergrades somewhat with subsp. pseudopubescens. Occasional long-spikelet specimens exhibit morphological characteristics of D. oligosanthes and D. commutatum.


Dichanthelium ovale subsp. praecocius (Hitchc. & Chase) Freckmann & Lelong

Basal blades 1-3 cm, sparsely to densely evenly pilose. Culms less than 1 mm thick, wiry; internodes with soft, spreading or retrorse papillose-based hairs longer than 4 mm. Cauline sheaths with soft, spreading or retrorse hairs, hairs usually longer than 4 mm, papillose-based; ligules 3-4 mm; blades 2-6 mm wide, both surfaces densely pilose. Spikelets 1.8-2.1 mm, obovoid or ellipsoid, pilose with papillose-based hairs.

Dichanthelium ovale subsp. praecocius is most common in the midwest and in the tallgrass prairie states. It intergrades with subsp. villosissimum, especially in the western parts of the latters range, and to a lesser extent, with D. acuminatum subsp. fasciculatum in the northern part of its range.


Dichanthelium ovale subsp. pseudopubescens (Nash) Freckmann & Lelong

Basal blades 2-6 cm, evenly pilose. Culms more than 1 mm thick, stiff; lower internodes sparsely pubescent, with ascending or appressed hairs, hairs shorter than 4 mm, not papillose-based. Cauline sheaths with sparse, ascending or appressed hairs, hairs shorter than 4 mm, often with shorter hairs underneath, not papillose-based; ligules 1-4 mm; blades 3-8 mm wide, both surfaces sparsely appressed-pubescent, margins ciliate basally, scabridulous elsewhere. Spikelets 2.1-2.6 mm, ellipsoid or obovoid-ellipsoid, with papillose-based hairs.

Dichanthelium ovale subsp. pseudopubescens grows in dry, sandy, open woods, sandhills, and sand dunes, over the same geographic range and in the same habitats as subsp. villosissimum, and often intergrades morphologically with that subspecies.


Dichanthelium ovale subsp. villosissimum (Nash) Freckmann & Lelong

Basal blades 3-7 cm, evenly long pilose. Culms more than 1 mm thick, stiff, often decumbent or prostrate in the fall; internodes with soft, spreading or retrorse, papillose-based hairs, hairs longer than 4 mm. Cauline sheaths with soft, spreading or retrorse hairs, hairs longer than 4 mm, papillose-based; ligules 2-5 mm; blades 6-10 mm wide, both surfaces densely pilose, hairs longer than 4 mm, margins short-ciliate basally, scabridulous and faintly whitish elsewhere. Spikelets 2.1-2.5 mm, usually ellipsoid, with dense, spreading, papillose-based hairs. Lower glumes 1/3-1/2 as long as the spikelets, usually acute. 2n = 18.

Dichanthelium ovale subsp. villosissimum grows in dry, sandy, open pine and oak woodlands. It and subsp. pseudopubescens are the most common and widespread subspecies throughout the eastern United States. The range of subsp. villosissimum extends to Mexico, Honduras, Guatemala, and Nicaragua. It grades into the less pubescent subsp. pseudopubescens, and occasional specimens with smaller spikelets approach D. acuminatum subsp. acuminatum, which is usually densely grayish, velvety-pubescent.


16.   Dichanthelium wrightianum (Scribn.) Freckmann
Wright's Panicgrass

Plants cespitose, with few culms per clump. Basal rosettes well-differentiated; blades ovate to lanceolate. Culms 15-50 cm tall (rarely taller), 0.3-0.8 mm thick, delicate, erect or ascending; nodes slightly swollen, often purplish or darker green than the internodes; internodes usually puberulent; fall phase branching profusely from the lower and midculm nodes, secondary branches and secondary panicles numerous, usually not greatly reduced. Cauline leaves 4-7; sheaths mostly puberulent or glabrous, margins finely ciliate; ligules 1.5-3 mm, of hairs; blades 2-4.5 cm long, 2-5 mm wide, ascending or spreading, occasionally involute, finely appressed-pilose adaxially, puberulent abaxially, bases rounded, margins finely whitish-scabridulous. Primary panicles 2.5-5.5 cm, 1/3-2/3 as wide as long, well-exserted; rachises and branches glabrous or sparsely puberulent (at least basally); ultimate branchlets and pedicels glabrous, somewhat viscid. Spikelets 0.8-1.1 mm, ellipsoid to nearly ovoid, often purplish, puberulent or subglabrous, obtuse or subacute. Lower glumes 1/4-1/3 as long as the spikelets, subacute; upper glumes shorter than the lower lemmas; lower florets sterile; upper florets 0.7-0.9 mm, ellipsoid, subacute. 2n = 18.

Dichanthelium wrightianum grows in moist, sandy or peaty areas, low pine savannahs, bogs, the margins of ponds, and cypress swamps, in the coastal plain from Massachusetts to Texas and Florida, extending to Cuba, Mexico, Central America, and northern South America.

Occasional specimens of Dichanthelium wrightianum, particularly those with subglabrous spikelets, closely resemble D. chamaelonche. Others suggest Dichanthelium ensifolium, and a few unusually robust specimens closely approach D. acuminatum subsp. longiligulatum. All of these taxa often grow together in the same habitats.


Dichanthelium (Hitchc. & Chase) Gould sect. Dichanthelium

Plants cespitose, with caudices or knotty crowns. Basal rosettes well-differentiated. Culms 18-100 cm, decumbent to erect, usually glabrous; nodes bearded or glabrous; fall phase often much branched and rebranched, with smaller blades and panicles than those of the culms. Cauline leaves 3-7; sheaths usually glabrous, lower sheaths sometimes pilose; ligules 0.2-0.8 mm, of hairs, or absent. Primary panicles exserted. Spikelets ellipsoid to obovoid, glabrous or pubescent. Upper florets acute to obtuse.

Gene exchange between the subspecies of D. dichotomum, and between D. dichotomum and other species in the genus, appears to be rather common.


17.   Dichanthelium dichotomum (L.) Gould
Forked Panicgrass

Plants in small or large clumps, with knotty crowns. Basal rosettes well-differentiated; blades ovate to lanceolate. Culms 20-100 cm, decumbent to erect, sometimes geniculate; nodes usually glabrous, sometimes sparsely pilose or densely bearded with retrorse hairs; internodes often purplish or olive green, lowest internodes usually glabrous, varying to sparsely pubescent; fall phase usually branching freely, especially from the nodes above the middle, ultimately forming dense, reclining fascicles of divergent branchlets with numerous reduced, thin, often involute blades, secondary panicles often reduced, with few spikelets. Cauline leaves 4-7; sheaths usually shorter than the internodes, usually glabrous, occasionally the lower sheaths sparsely to densely soft-pubescent, sheaths of the uppermost leaves sometimes with whitish glandular spots between the prominent veins, margins of all sheaths glabrous or ciliate; ligules absent or shorter than 1 mm, of hairs; blades 3.5-14 cm long, 5-14 mm wide, usually thin, distant, spreading to reflexed or (occasionally) ascending, yellow-green to purplish, usually glabrous on both surfaces or (at least the lower blades) more or less densely and softly pubescent, bases constricted (in narrow-bladed subspecies) or narrowly subcordate (in wide-bladed subspecies), margins glabrous or ciliate basally, glabrous distally, blades of the flag leaves usually spreading. Primary panicles 3-12 cm, long-exserted, usually with many spikelets; branches wiry, mostly spreading or ascending, usually glabrous, sometimes scabridulous. Spikelets 1.5-2.7 mm, usually ellipsoid or obovoid, green or purplish (at least at the base), glabrous or (less commonly) sparsely pubescent or puberulent, often prominently veined, obtuse to acute to beaked. Lower glumes usually less than 1/3 as long as the spikelets, obtuse to acute; upper glumes usually slightly shorter than or as long as the lower lemmas and upper florets (occasionally extending beyond the floret); lower florets sterile; upper florets 1.3-2 mm long, usually less than 1 mm wide, ellipsoid, subacute to obtuse.

Dichanthelium dichotomum grows in dry, sandy, clayey, or rocky ground, often in woods, or (more commonly) in moist or wet places, including marshes, bogs, low woods, swamps, and the moist borders of lakes and ponds. Its range extends south from the Flora region into the Caribbean. It is a polymorphic and ubiquitous species, with many of its intergrading subspecies exhibiting traits of other widespread and variable species such as D. commutatum, D. laxiflorum, and D. sphaerocarpon, which often grow at the same sites.

1
Lower nodes hairy (2)
Lower nodes glabrous (5)
2
Spikelets 1.5-1.8 mm long, upper floret 0.6-0.8 mm wide ..... subsp. microcarpon
Spikelets 1.8-2.5 mm long; upper floret 0.7-1.0 mm wide (3)
3
Spikelets usually glabrous; midculm blades usually 5-7 mm wide ..... subsp. dichotomum
Spikelets pubescent; midculm blades usually 7-14 mm wide (4)
4
Lower sheaths and blades glabrous or sparsely pubescent ..... subsp. nitidum
Lower sheaths and blades more or less densely velvety pubescent ..... subsp. mattamuskeetense
5
Larger blades more than 1 cm wide; sheaths often with pale glandular spots between the prominent veins; spikelets 1.9-2.6 mm long, acute to beaked ..... subsp. yadkinense
Larger blades less than 1 cm wide; sheaths without glandular spots; spikelets 1.5-2.3 mm long, obtuse to subacute (6)
6
Culms weak, ultimately reclining or sprawling, often flattened ..... subsp. lucidum
Culms erect, terete (7)
7
Blades usually spreading; spikelets ellipsoid, 1.8-2.3 mm long, rarely purplish at the base ..... subsp. dichotomum
Blades usually ascending or erect; spikelets broadly ellipsoid or obovoid, 1.5-1.8 mm long, often purplish at the base ..... subsp. roanokense


Dichanthelium dichotomum (L.) Gould subsp. dichotomum

Culms 20-60 cm, usually slender, erect; nodes usually glabrous, lowermost nodes sometimes sparsely bearded with soft, retrorse hairs; internodes terete, green to purplish, glabrous; fall phase branching freely from the midculm nodes, producing dense clusters of reduced, flat to involute blades and reduced secondary panicles. Cauline sheaths usually glabrous, lowermost sheaths sometimes sparsely pubescent, margins glabrous or short-ciliate; blades usually 3.5-9 cm long, usually 5-7 mm wide (seldom wider), usually spreading, narrowly lanceolate, glabrous on both surfaces, bases constricted. Primary panicles well-exserted; branches few, flexuous, with fewer spikelets than all the other subspecies apart from subsp. lucidum. Spikelets 1.8-2.3 mm, ellipsoid, usually glabrous, rarely purplish at the base; upper florets 1.7-2 mm long, 0.7-1.0 mm wide. 2n = 18.

Dichanthelium dichotomum subsp. dichotomum usually grows in dry to mesic woods. Its range extends from southern Ontario to Maine and south through Illinois and Missouri to eastern Texas and to the east coast and central Florida.


Dichanthelium dichotomum subsp. lucidum (Ashe) Freckmann & Lelong

Culms occasionally more than 60 cm, very slender, weak; nodes usually glabrous; internodes often flattened, green, glabrous; fall phase with reclining or decumbent culms and numerous axillary branches, branches elongated and widely divergent, not forming fascicles. Cauline sheaths usually shorter than the internodes, glabrous; blades slightly smaller than those of the other subspecies, ascending or spreading, often lustrous, bright green, glabrous throughout. Primary panicles slightly smaller and with fewer spikelets than in the other subspecies (particularly subsp. dichotomum, which it closely resembles). Spikelets 1.8-2.3 mm, ellipsoid, usually glabrous, obtuse to subacute; upper florets 1.7-2 mm. 2n = unknown.

Dichanthelium dichotomum subsp. lucidum grows in wet woods, the margins of cypress swamps, sphagnum bogs, and other similar, wet habitats. It is primarily a species of the coastal plain, ranging from New Jersey to Florida, southeastern Texas, and up the Mississippi embayment to western Tennessee and, as a disjunct, on the Indiana Dunes of Lake Michigan.


Dichanthelium dichotomum subsp. mattamuskeetense (Ashe) Freckmann & Lelong

Plants very similar to subsp. microcarpon. Fall phase sparingly branched, blades not as greatly reduced as in subsp. microcarpon. Sheaths and blades, particularly those of the lower leaves, more or less densely velvety pubescent. 2n = unknown.

Dichanthelium dichotomum subsp. mattamuskeetense grows in low, moist, often sandy or peaty, ground and bogs. A relatively uncommon subspecies, it grows on the Atlantic coastal plain from Massachusetts to Florida.


Dichanthelium dichotomum subsp. microcarpon (Muhl. ex Elliott) Freckmann & Lelong

Culms 30-100 cm, slender, erect or geniculate; fall phase freely branching from all nodes, reclining from masses of branchlets and numerous reduced, ciliate blades and secondary panicles; nodes conspicuously bearded with retrorse hairs. Sheaths usually glabrous, lowermost sheaths sometimes sparsely pubescent, occasionally with whitish spots between the veins, ciliate along the margins; blades 5-14 cm long, 5-14 mm wide, thin, spreading to reflexed, glabrous on both surfaces, bases with few to many papillose-based cilia. Panicles 5-12 cm, well-exserted, dense. Spikelets 1.5-1.8 mm, usually glabrous, rarely slightly pubescent. Lower glumes usually less than 1/4 as long as the spikelets; upper glumes usually shorter than the lower lemmas; upper florets 1.3-1.6 mm long, 0.6-0.8 mm wide, subacute. 2n = 18.

Dichanthelium dichotomum subsp. microcarpon grows in wet woods, swamps, and wetland borders. It is a widespread subspecies, extending from southern Michigan to Massachusetts and south to eastern Oklahoma and Texas and throughout the southeast to central Florida.


Dichanthelium dichotomum subsp. nitidum (Lam.) Freckmann & Lelong

Plants very similar in most respects to subsp. microcarpon. Fall phase freely branching from all nodes, reclining from masses of branchlets and numerous reduced, ciliate blades and secondary panicles. Cauline sheaths and blades usually glabrous, lower sheaths and blades sometimes sparsely pubescent. Spikelets 1.8-2.5 mm (rarely longer), puberulent or pubescent. Lower glumes less than 1/3 as long as the spikelets, subacute; upper glumes and lower lemmas subequal; upper florets 1.7-2 mm long, 0.7-1.0 mm wide, subobtuse. 2n = unknown.

Dichanthelium dichotomum subsp. nitidum grows in moist to wet areas, and the borders of swamps. It is primarily a coastal plain taxon, ranging from Virginia to southeastern Texas and Florida.

Dichanthelium dichotomum subsp. nitidum is very similar to both subsp. microcarpon and subsp. mattamuskeetense, and intergrades with each occasionally.


Dichanthelium dichotomum subsp. roanokense (Ashe) Freckmann & Lelong

Culms to 100 cm, erect; nodes usually glabrous; internode s terete, usually glabrous, often slightly glaucous, sometimes olivaceous; fall phase with erect or decumbent culms, branching at the mid- and upper culm nodes, with numerous axillary branches, branches elongated and widely divergent, not forming fascicles. Cauline sheaths glabrous or the lowest sheaths sparsely pubescent; blades usually 5-8 mm wide, stiffly ascending or erect, often olivaceous or purplish abaxially, glabrous or sparsely pubescent basally. Spikelets 1.5-1.8 mm (seldom longer), broadly ellipsoid or obovoid, often purplish at the base, glabrous, obtuse to subacute. Upper florets 1.4-1.6 mm, broadly ellipsoid. 2n = unknown.

Dichanthelium dichotomum subsp. roanokense grows in marshes, wet pinelands, wet woods, and the borders of swamps. A relatively uncommon subspecies, it grows on the coastal plain from Delaware to southeastern Texas and in the West Indies. It is very similar to subsp. dichotomum and also exhibits traits of D. sphaerocarpon and D. erectifolium.


Dichanthelium dichotomum subsp. yadkinense (Ashe) Freckmann & Lelong

Culms 50-100 cm; nodes usually glabrous; internodes usually glabrous, often yellowish-green; fall phase suberect, sparsely branched from the midculm nodes, blades not as greatly reduced as in the other subspecies. Cauline sheaths glabrous, often with pale glandular spots between the prominent veins; blades 9-14 cm long, 7-12 mm wide, thin, widest near the middle and tapering to both ends, glabrous on both surfaces. Spikelets 1.9-2.6 mm, elliptic to subfusiform, glabrous, apices acute or beaked. Upper florets 1.8-2 mm. 2n = 18.

Dichanthelium dichotomum subsp. yadkinense grows in rich, moist or wet woods. A relatively uncommon subspecies, its range extends from Pennsylvania to Maryland and south through southern Illinois and southeastern Missouri to Georgia and Louisiana, but not to Florida. It exhibits traits of D. laxiflorum and D. commutatum.


18.   Dichanthelium boreale (Nash) Freckmann
Northern Panicgrass, Panic Boreal

Plants cespitose. Basal rosettes well-differentiated; blades 2-4 cm, pubescent, reddish. Culms 18-75 cm, usually more than 1 mm thick, occasionally delicate, erect or ascending; nodes glabrous; internodes glabrous; fall phase with decumbent culms, branches arising from the lower and midculm nodes, rebranching 2-3 times, with small blades and secondary panicles compared to those on the culms, secondary panicles with 8-10 spikelets, partially included at maturity. Cauline leaves 3-5; sheaths shorter than the internodes, lower sheaths pubescent, upper sheaths glabrous, margins of all sheaths sparsely ciliate; ligules about 0.5 mm, of hairs; blades 5-11 cm long, 5-13 mm wide, thin, spreading to erect, usually glabrous, rarely pubescent abaxially, always glabrous adaxially, bases truncate to cordate, ciliate on the margins, blades of the flag leaves erect or ascending. Primary panicles 5-11 cm long, 3-8 cm wide, ovoid, long-exserted, with 40-220 spikelets. Spikelets 2-2.2 mm long, 0.8-1.3 mm wide, ellipsoid, usually reddish, shortly pubescent, subacute. Lower glumes 0.5-1 mm, triangular-ovate; lower florets sterile; upper florets slightly exceeding the upper glumes and lower lemmas, subacute. 2n = 18.

Dichanthelium boreale grows inopen woodlands and thickets, wet meadows, and fields within the Flora region. The primary panicles are mostly open-pollinated and are produced in May and June; the secondary panicles are predominantly cleistogamous and are produced from mid-June into October.

Dichanthelium boreale occasionally hybridizes with D. acuminatum and D. xanthophysum, producing a sterile triploid sometimes called Panicum calliphyllum Ashe.


Dichanthelium sect. Nudicaulia Freckmann & Lelong

Plants cespitose. Basal rosettes somewhat differentiated. Culms 20-60 cm, weakly ascending, glabrous; fall phase rarely branching from near the base. Cauline leaves 3-4; sheaths sparsely pilose or glabrous; ligules membranous, ciliate; blades mostly basal, flat to stiffly involute, ascending to erect, uppermost blades much reduced. Primary panicles long-exserted, with few spikelets. Spikelets 2.4-3.2 mm, narrowly ellipsoid to ovoid, glabrous. Upper florets acute.

Dichanthelium nudicaule is the only member of sect. Nudicaulia present in the Flora region.


19.   Dichanthelium nudicaule (Vasey) B.F. Hansen & Wunderlin
Naked-Stemmed Panicgrass

Plants cespitose, clumps with few culms. Basal rosettes somewhat differentiated; blades lanceolate. Culms 20-60 cm, with caudices, slender, glabrous, weakly ascending, with a tuft of predominantly basal leaves, only the upper 3 internodes elongated; fall phase rarely branching, branches, if present, from the basal and subbasal nodes, erect. Cauline leaves 3-4; sheaths longer than the internodes, lower sheaths sparsely ascending to spreading-pilose, upper sheaths somewhat elongate, striate, glabrous, lustrous; ligules usually 0.5-1 mm, membranous, ciliate; blades 2-20 cm long, 3-10 mm wide, mostly basal, ascending to erect, widest near midlength, flat to stiffly involute, tapering basally and partly encircling the culm, glabrous, blades of the flag leaves distant from and much smaller than those below. Primary panicles 2-7 cm long, almost as wide when expanded, long-exserted, sparse; branches few, ascending to spreading, glabrous or scabridulous. Spikelets 2.4-3.2 mm long, usually less than 1 mm wide, narrowly ellipsoid to ovoid, often purplish-stained, glabrous. Lower glumes less than 1/3 as long as the spikelets, acute; upper glumes and lower lemmas clearly longer than the upper florets, prominently veined, apices acuminate and usually beaked; lower florets sterile; upper florets about 2 mm long, about 1 mm wide, ellipsoid, acute. 2n = unknown.

Dichanthelium nudicaule is a rare species that grows in wet pine savannas, bogs (including Sphagnum mats), and the margins of cypress swamps in eastern Louisiana, southern Mississippi and Alabama, and western Florida. Vegetatively, it exhibits traits of D. laxiflorum, but its spikelets resemble those of small plants of D. scabriusculum, which are fairly widespread in similar habitats of the Gulf coastal plain. Dichanthelium nudicaule is protected by U.S. federal law.


Dichanthelium sect. Ensifolia (Hitchc.) Freckmann & Lelong

Plants cespitose, with caudices. Basal rosettes well-differentiated. Culms 5-60 cm tall, 0.2-0.8 (1.6) mm thick, erect or reclining, sometimes geniculate at the lower nodes, glabrous or sparsely pubescent near the bases; fall phase branching from the lower and midculm nodes. Cauline leaves 3-9; sheaths glabrous or sparsely pilose, usually ciliate; ligules 0.2-1.8 mm, of hairs; blades usually 2-5 cm, sometimes with prominent white, cartilaginous margins. Spikelets 1.1-1.7 mm, ellipsoid to narrowly obovoid, glabrous or puberulent. Upper florets subacute to acute.


20.   Dichanthelium ensifolium (Baldwin ex Elliott) Gould
Sword-Leaf Panicgrass

Plants cespitose, with caudices. Basal rosettes well-differentiated; blades 1.5-6 cm, ovate to lanceolate, soft, glabrous. Culms 10-40 cm tall, 0.2-0.8 (1.6) mm thick, weak, erect or reclining; nodes usually glabrous, sometimes sparsely bearded; internodes usually glabrous, occasionally sparsely pubescent; fall phase with spreading culms, sparingly branched, branching mostly from the midculm nodes, occasionally producing small fascicles of leafy branchlets. Cauline leaves 4-9; sheaths much shorter than the internodes, prominently veined, glabrous or sparsely pilose and ciliate, particularly at the top; ligules 0.2-1.8 mm, often more than 1 mm, of hairs, without adjacent pseudoligules; blades 1.5-3.5 cm long (seldom longer), 1.5-4 mm wide, all similar in size, thin, spreading or reflexed, abaxial surfaces puberulent, at least apically, or sparsely pilose, adaxial surfaces glabrous or sparsely pilose, at least basally, bases abruptly and strongly constricted, occasionally ciliate, margins entire or faintly scabridulous, rarely white-cartilaginous. Primary panicles 1.5-4 cm, nearly as wide as long, long-exserted; branches wiry, mostly spreading, minutely scabridulous. Spikelets 1.2-1.5 mm, ellipsoid to obovoid, yellow-green to purplish, puberulent or glabrous, subacute or obtuse. Lower glumes seldom more than 1/4 as long as the spikelets, acute or obtuse; upper glumes usually slightly shorter than the lower lemmas and upper florets, not strongly veined; upper florets 1.1-1.4 mm long, less than 1 mm wide, ellipsoid, acute. 2n = 18.

Dichanthelium ensifolium grows in wet to moist, sandy pinelands, savannahs, and bogs, often on Sphagnum mats, primarily on the coastal plain. It extends south into Mesoamerica, and has been reported from Venezuela. Occasional specimens grade towards the larger D. tenue, and are usually found on somewhat drier sites. It also resembles D. chamaelonche, but that species is usually more densely cespitose, has slightly smaller, glabrous spikelets, and generally occupies drier, disturbed sites.

The two subspecies are sympatric, often growing together at the same sites.

1
Sheaths sparsely spreading-pilose; ligules usually 1-1.8 mm long; blades sparsely pilose or glabrous on both surfaces ..... subsp. curtifolium
Sheaths glabrous; ligules 0.2-1 mm long; blades usually puberulent abaxially, usually glabrous, occasionally pubescent adaxially ..... subsp. ensifolium


Dichanthelium ensifolium subsp. curtifolium (Nash) Freckmann & Lelong

Cauline sheaths sparsely spreading-pilose; ligules usually 1-1.8 mm; blades sparsely pilose or glabrous on both surfaces.


Dichanthelium ensifolium (Baldwin ex Elliott) Gould subsp. ensifolium

Cauline sheaths glabrous; ligules 0.2-1 mm; blades usually puberulent abaxially, glabrous or, occasionally, pubescent adaxially.


21.   Dichanthelium tenue (Muhl.) Freckmann & Lelong
Slender Panicgrass

Plants cespitose, with caudices, forming small, often rather dense clumps with few culms. Basal rosettes well-differentiated; blades 1-5 cm, ovate to lanceolate. Culms 15-55 cm tall, 0.2-0.8 mm thick, erect from geniculate bases; nodes glabrous; internodes mostly glabrous, or the lowest internodes sparsely appressed-pubescent basally; fall phase branching sparingly from the lower and midculm nodes. Cauline leaves 3-4; sheaths much shorter than the internodes, prominently veined, mostly glabrous, margins occasionally ciliate, ligules 0.2-0.7 mm, of hairs, without adjacent pseudoligules; blades 2-6 cm long, 1.5-6 mm wide, ascending, distant, flat, relatively thick, glabrous on both surfaces or the abaxial surfaces minutely puberulent, bases rounded, margins more or less prominently whitish-scabridulous, blades of the flag leaves much shorter than those of the lower leaves. Primary panicles 3-6 cm, nearly as wide as long, long-exserted, dense; branches wiry, spreading to ascending, usually scabridulous. Spikelets 1.3-1.7 mm long, less than 1 mm wide, ellipsoid, often purplish, densely puberulent, obtuse or subacute. Lower glumes usually less than 1/4 as long as the spikelets, broadly acute or obtuse; upper glumes and lower lemmas subequal, or the glumes slightly shorter, exceeded by the upper florets; lower florets sterile; upper florets 1.3-1.6 mm, ellipsoid, subacute. 2n = 18.

Dichanthelium tenue grows in moist to dry, sandy woods, savannahs, and disturbed sites. It also grows in Chiapas, Mexico (Zuloaga et al. 1993). It exhibits features of D. sphaerocarpon and D. dichotomum. It is also closely related to D. ensifolium, and occasional specimens are intermediate between them.


22.   Dichanthelium chamaelonche (Trin.) Freckmann & Lelong
Small-Seeded Panicgrass

Plants usually densely cespitose, with caudices. Basal rosettes well-differentiated; blades 1-5 cm, ovate to lanceolate. Culms 5-45 cm tall, 0.2-0.8 mm thick, erect, often purplish; nodes glabrous or sparsely pubescent; internodes often ascending-pubescent below; fall phase branching extensively from the basal nodes, usually forming very dense cushions. Cauline leaves 3-5; sheaths mostly shorter than the internodes, often purplish, glabrous or sparsely pubescent, margins often sparsely ciliate; ligules 0.2-0.5 mm, of hairs, without adjacent pseudoligules; blades 2-5 cm long (rarely longer), 1-4 mm wide, flat or involute, rather firm, ascending, often purplish, usually glabrous on both surfaces, bases subcordate, often with a few long, stiff cilia, margins narrowly white, cartilaginous, and scabridulous, blades of the flag leaves only slightly shorter than those of the lowerleaves. Primary panicles 1.5-5 cm (seldom longer), nearly as wide as long, delicate, dense; branches numerous, flexuous, spreading, often purplish, glabrous or faintly scabridulous. Spikelets 1.1-1.5 mm long, 0.7-1 mm wide, broadly ellipsoid or obovoid, often purple-tinged, glabrous or puberulent, obtuse or subacute. Lower glumes approximately 1/3 as long as the spikelets, broadly acute or obtuse; upper glumes and lower lemmas subequal or the glumes slightly shorter than the lemmas; lower florets sterile; upper florets 0.9-1.2 mm, ellipsoid, apices exceeding the upper glumes and lower lemmas, subacute.

Dichanthelium chamaelonche grows in low, open, sandy, coastal pine woods, savannahs, and moist depressions in sand dunes. It is restricted to the southeastern United States.

1
Culms 5-20 cm tall, glabrous or puberulent; spikelets 1.3-1.5 mm long, puberulent ..... subsp. breve
Culms 10-45 cm tall, glabrous; spikelets 1.1-1.4 mm long, glabrous ..... subsp. chamaelonche


Dichanthelium chamaelonche subsp. breve (Hitchc. & Chase) Freckmann & Lelong

Culms 5-20 cm, glabrous or puberulent. Sheaths puberulent or glabrous; blades strongly involute, often arcuate, puberulent or glabrous on both surfaces. Primary panicles usually barely exserted above the dense basal tuft of blades. Spikelets 1.3-1.5 mm, puberulent. 2n = unknown.

Dichanthelium chamaelonche subsp. breve grows only in peninsular Florida.


Dichanthelium chamaelonche (Trin.) Freckmann & Lelong subsp. chamaelonche

Culms 10-45 cm, glabrous. Cauline sheaths glabrous; blades flat or involute, glabrous on both surfaces. Primary panicles well-exserted above the basal tuft of blades. Spikelets 1.1-1.4 mm, glabrous. 2n = 18.

Dichanthelium chamaelonche subsp. chamaelonche grows from North Carolina to Florida and Louisiana.


Dichanthelium sect. Sphaerocarpa (Hitchc. & Chase) Freckmann & Lelong

Plants cespitose, with caudices. Basal rosettes well-differentiated; blades large, ovate-lanceolate. Culms 15-95 cm, usually nearly erect, sometimes spreading to ascending, glabrous or almost glabrous, slightly fleshy or thickened; fall culms with sparse branching. Cauline leaves 3-7, glabrous or almost glabrous throughout; ligules almost obsolete, usually of hairs shorter than 0.8 mm, sometimes with a minute membranous base; blades firm, thick, margins cartilaginous, bases cordate, ciliate. Spikelets 1-1.8 mm, spherical to broadly obovoid, puberulent or sometimes glabrous. Upper florets blunt or minutely umbonate.

Dichanthelium sect. Sphaerocarpa extends from the southeastern United States through Central America and Cuba to northern South America. Pairs of species often grow together, with infrequent apparent hybridization.


23.   Dichanthelium erectifolium (Nash) Gould & C.A. Clark
Florida Panicgrass

Plants cespitose, with few culms. Basal rosettes well-differentiated; blades numerous, to 15 cm, lowest blades ovate, upper blades lanceolate, grading into the cauline blades. Culms 30-75 cm, nearly erect, stiff, slightly fleshy or thickened; nodes glabrous, often with a constricted, yellowish ring; internodes glabrous; fall phase with few, long, suberect branches, sparingly rebranched, branches arising mostly from near the base. Cauline leaves 4-7; sheaths shorter than the internodes, mostly glabrous, margins ciliate; ligules 0.2-0.5 mm; blades 5-10 cm long, 5-10 mm wide, stiffly ascending, thick, glabrous, veins evident, bases cordate, with papillose-based cilia, margins whitish, cartilaginous. Primary panicles 5-14 cm, 1/2-2/3 as wide as long, exserted. Spikelets 1-1.4 mm, broadly obovoid-spherical, puberulent to subglabrous. Lower glumes 0.2-0.4 mm, acute, upper florets 0.8-1.1 mm, broadly ellipsoid, minutely umbonate. 2n = unknown.

Dichanthelium erectifolium grows in sand and peat in wet pinelands, bogs, and the shores of ponds. Its range extends from the southeastern Flora region into the Caribbean.


24.   Dichanthelium polyanthes (Schult.) Mohlenbr.
Many-Flowered Panicgrass

Plants cespitose, with few culms per tuft. Basal rosettes well-differentiated; blades 3-8 cm long, often to 2 cm wide, ovate-lanceolate. Culms 30-95 cm, nearly erect, fairly stout; nodes glabrous or puberulent; internodes usually glabrous; fall phase with few, long-ascending branches, sparingly rebranched, branches arising mostly near the base of the culms. Cauline leaves 4-7; sheaths shorter than the internodes, mostly glabrous, margins ciliate; ligules vestigial; blades 10-25 cm long, 14-25 mm wide, thick, firm, often light green, veins evident (some more prominent than others), bases cordate, with papillose-based cilia, margins whitish, cartilaginous. Primary panicles 7-20 cm, less than 1/2 as wide as long, exserted. Spikelets 1.3-1.7 mm, broadly ellipsoid-spherical, often purplish at the base, puberulent. Lower glumes 0.4-0.7 mm, acute to obtuse, upper florets 1.1-1.4 mm, broadly ellipsoid, blunt. 2n = 18.

Dichanthelium polyanthes grows in woods, stream banks, and ditches, and is restricted to the eastern United States. It occasionally hybridizes with D. sphaerocarpon.


25.   Dichanthelium sphaerocarpon (Elliott) Gould
Round-Fruited Panicgrass

Plants cespitose. Basal rosettes well-differentiated; blades 2-6 cm long, about 1 cm wide, ovate, the uppermost leaves often resembling the lower cauline blades. Culms 15-50 cm, few together, decumbent or ascending, light green, glabrous, slightly fleshy or thickened; fall phase branching mostly near the bases, with sparse branching; nodes appressed-pubescent or glabrous. Cauline leaves 3-4(6); sheaths sometimes overlapping near the bases, glabrous, margins ciliate; ligules almost obsolete, or of 0.2-0.8 mm hairs from a tiny membranous base; blades 1.5-10 cm long, 5-14 mm wide, thick, light green, faintly veined, bases cordate, with papillose-based cilia, margins white, cartilaginous. Primary panicles 4-14 cm, more than 1/2 as wide as long, usually long-exserted. Spikelets 1.4-1.8 mm, broadly obovoid-spherical, usually puberulent, sometimes glabrous. Lower glumes 0.4-0.8 mm, acute to obtuse, upper florets 1.1-1.5 mm, broadly ellipsoid, blunt. 2n = 18.

Dichanthelium sphaerocarpon grows in dry, open woods and roadsides. Its range extends from eastern North America to Ecuador and Venezuela. It occasionally hybridizes with several other species, including D. polyanthes, D. acuminatum, and D. laxiflorum.


Dichanthelium sect. Lancearia (Hitchc.) Freckmann & Lelong

Plants usually densely cespitose, with caudices. Basal rosettes usually well-differentiated. Culms slender, usually purplish and puberulent; fall phase often profusely branched and rebranched. Cauline leaves 8-14; sheaths usually purplish and puberulent; ligules less than 0.5 mm, of hairs; blades usually purplish and puberulent. Primary panicles exserted. Spikelets 1.5-2.6 mm, obovoid-pyriform, planoconvex in side view, bases attenuate. Lower glumes thin, weakly veined, attached about 0.2 mm below the upper glumes, clasping at the base. Upper florets subacute.

Only one species of sect. Lancearia, Dichanthelium portoricense, grows in the Flora region.


26.   Dichanthelium portoricense (Desv. ex Ham.) B.F. Hansen & Wunderlin
Blunt-Glumed Panicgrass

Plants usually densely cespitose. Basal rosettes well-differentiated; blades 1.5-6 cm, ovate to lanceolate. Culms 15-50 cm, slender, wiry; internodes olive green to purplish, densely puberulent or glabrous; fall phase spreading or decumbent, branching extensively from the lower and midculm nodes, producing numerous congested fascicles of reduced, flat or involute blades and reduced secondary panicles. Cauline leaves 4-7; sheaths much shorter than the internodes, densely crisp-puberulent, velvety-puberulent, or glabrous, often ciliate along the margins; ligules shorter than 0.5 mm; blades 2-7 cm long (seldom longer), 2.5-8 mm wide (rarely wider), spreading, firm, flat or slightly involute, without prominently raised veins, not longitudinally wrinkled, densely puberulent or glabrous abaxially, glabrous, sparsely puberulent, or pubescent adaxially, bases subcordate, with papillose-based cilia, margins often whitish and scabridulous. Primary panicles 2-7 cm long, 2/3 to nearly as wide as long, with relatively few spikelets, exserted; branches flexuous, spreading or reflexed, scabridulous to densely puberulent. Spikelets 1.5-2.6 mm, obovoid-pyriform, planoconvex in side view, puberulent, pubescent, or glabrous, attenuate basally, apices usually broadly rounded. Lower glumes 0.6-1.4 mm, thin, weakly-veined, attached about 0.2 mm below the upper glumes, clasping at the base; upper glumes as long as or slightly shorter than the lower lemmas; upper florets 1.4-2 mm, broadly ellipsoid, apices subacute, minutely puberulent. 2n = 18.

Dichanthelium portoricense grows in sandy woods, low pinelands, savannahs, and coastal sand dunes, usually in moist places. Its range extends south from the Flora region into Mexico, the Caribbean, and Mesoamerica. It is a highly variable species with numerous intergrading forms, some possibly resulting from hybridization with other widespread species in the same region, such as D. sphaerocarpon and D. commutatum.

1
Spikelets 1.8-2.6 mmlong, usually densely pubescent or puberulent (rarely glabrous); cauline blades 4-7 cm long, 3.5-8 mm wide ..... subsp. patulum
Spikelets 1.5-2.0 mm long, puberulent to nearly glabrous; cauline blades 2-5 cm long, 2.5-4.5 mm wide ..... subsp. portoricense


Dichanthelium portoricense subsp. patulum (Scribn. & Merr.) Freckmann & Lelong

Culms 20-50 cm, often densely puberulent. Sheaths puberulent to subglabrous. Cauline blades 4-7 cm long, 3.5-8 mm wide. Primary panicles 2-7 cm. Spikelets 1.8-2.6 mm, usually densely pubescent or puberulent, rarely glabrous.

Dichanthelium portoricense subsp. patulum is more common in moist, sandy pinelands and savannahs than subsp. portoricense. It also grows in coastal sand dunes, but is less abundant there than subsp. portoricense. It is the more variable of the two subspecies, grading into subsp. portoricense as well as D. commutatum. More robust plants are recognized by some as Panicum patentifolium Nash. Occasional specimens, recognized by some as P. webberianum Nash, resemble the widespread D. sphaerocarpon.


Dichanthelium portoricense (Desv. ex Ham.) B.F. Hansen & Wunderlin subsp. portoricense

Culms 15-40 cm, glabrous or puberulent. Sheaths glabrous or puberulent; cauline blades 2-5 cm long, 2.5-4.5 mm wide, usually puberulent abaxially and glabrous adaxially. Primary panicles 2-4.5 cm. Spikelets 1.5-2.0 mm, puberulent to nearly glabrous.

Dichanthelium portoricense subsp. portoricense is more common than subsp. patulum in coastal sand dunes. It also grows in sandy pinelands and savannahs. It resembles D. aciculare somewhat, but that species usually has ascending-pilose culms, strongly involute or acicular blades, and longer spikelets.


Dichanthelium sect. Angustifolia (Hitchc.) Freckmann & Lelong

Plants grayish-green, densely cespitose, with caudices. Basal rosettes sometimes poorly differentiated. Culms 15-75 cm, erect; fall phase erect or spreading, extensively branched from the mid- and upper culm nodes, secondary panicles and blades of the fascicles much reduced. Cauline leaves 3-7; sheaths glabrous, pilose, or villous, pubescence sometimes sparse; ligules 0.5-2 mm, of hairs, sometimes with a pseudoligule of adjacent longer hairs; blades narrow, stiffly ascending to erect, lower blades widest, transitional to the rosette blades, often longitudinally wrinkled, midculm blades generally 16-25 times longer than wide, with prominent raised veins, blades of the flag leaves much reduced, often involute. Primary panicles usually long-exserted. Spikelets ellipsoid to obovoid, narrow to attenuate basally, biconvex in side view. Lower glumes thin, obtuse, weakly veined, somewhat remote and clasping at the base; upper glumes with 5-9 prominent veins. Upper florets blunt to apiculate.

Dichanthelium sect. Angustifolia grows from the southeastern United States through Central America and the West Indies to northern South America.


27.   Dichanthelium aciculare (Desv. ex Poir.) Gould & C.A. Clark
Narrow-Leaved Panicgrass

Plants grayish-green, cespitose, with caudices. Basal rosettes poorly differentiated; blades usually large, ovate to lanceolate, often transitional to the cauline blades. Culms 15-75 cm, erect; nodes glabrous or sparsely pubescent; internodes glabrous or puberulent to pilose basally; fall phase with erect to spreading culms, extensively branched from the mid- and upper culm nodes, eventually producing flabellate clusters of reduced, flat or involute blades. Cauline leaves 3-7; sheaths shorter than the internodes, glabrous or with soft, ascending, papillose-based hairs; ligules 0.5-2 mm, of hairs; lower blades 4-16 cm long, 3-9 mm wide, stiffly ascending to erect, glabrous or sparsely pilose to pubescent, with prominent raised veins, flat or longitudinally wrinkled, blades of the flag leaves often greatly reduced, often involute. Primary panicles 2-10 cm long, 0.5-7 cm wide, open or contracted, well-exserted. Spikelets 1.7-3.6 mm long, 1.2-1.8 mm wide, obovoid to ellipsoid, biconvex in side view, glabrous or pubescent, bases narrow to attenuate, apices blunt or pointed to beaked. Lower glumes thin, weakly veined, about 1/3 as long as the spikelets, attached to 0.5 mm below upper glumes, clasping at the base, broadly triangular to rounded; upper glumes with 5-9 prominent veins; lower florets sterile; upper florets apiculate. 2n = 18.

Dichanthelium aciculare grows in sandy, open areas in the southeastern United States, the West Indies and the Caribbean, southern Mexico, Central America, and northern South America. It has not been reported from northernMexico. The primary panicles are open-pollinated (sometimes briefly) and develop from April to June; the secondary panicles are cleistogamous and develop from May into late fall.

The subspecies are often distinct when growing together, perhaps maintained by the predominant autogamy, but they are more difficult to separate over wider geographic areas. Rare, partly fertile putative hybrids with Dichanthelium consanguineum, D. acuminatum, D. ovale, D. portoricense, and (possibly) D. dichotomum apparently lead to some intergradation with these species.

1
Primary panicles usually contracted; branches appearing 1-sided; culms sparsely pubescent to almost glabrous ..... subsp. neuranthum
Primary panicles not contracted; branches not appearing 1-sided; culms usually pubescent, at least on the lower internodes (2)
2
Spikelets 1.7-2.3 mm long, with blunt apices ..... subsp. aciculare
Spikelets 2.4-3.6 mm long, with pointed or beaked apices (3)
3
Spikelets 2.4-3 mm long, not strongly attenuate at the base; lower glumes attached less than 0.2 mm below the upper glumes ..... subsp. angustifolium
Spikelets 2.9-3.6 mm long, strongly attenuate at the base; lower glumes attached 0.3-0.5 mm below the upper glumes ..... subsp. fusiforme


Dichanthelium aciculare (Desv. ex Poir.) Gould & C.A. Clark subsp. aciculare

Plants densely cespitose. Culms usually 15-35 cm, usually pubescent, at least on the lower internodes; nodes sometimes bearded, usually yellowish; lower internodes puberulent to appressed-pilose. Cauline blades usually 4-6 cm. Primary panicles usually open, branches spreading to ascending, not appearing 1-sided. Spikelets 1.7-2.3 mm, obovoid, blunt.

Dichanthelium aciculare subsp. aciculare is common in sterile, open sands on the coastal plain.


Dichanthelium aciculare subsp. angustifolium (Elliott) Freckmann & Lelong

Plants cespitose. Culms usually 35-75 cm, usually pubescent, at least on the lower internodes. Midculm blades 6-16 cm, usually glabrous. Primary panicles open, branches spreading, not appearing 1-sided. Spikelets 2.4-3 mm, narrowly obovoid to ellipsoid, often pointed to beaked. Lower glumes attached less than 0.2 mm below the upper glumes.

Dichanthelium aciculare subsp. angustifolium grows in open pine woodlands, often in sandy soil with needle duff.


Dichanthelium aciculare subsp. fusiforme (Hitchc.) Freckmann & Lelong

Resembles subsp. angustifolium vegetatively except that the culms are often taller and more slender. Panicle branches ascending, not appearing 1-sided. Spikelets 2.9-3.6 mm, fusiform, bases strongly attenuate, apices pointed or beaked, lower glumes attached 0.3-0.5 mm below the upper glumes.

Dichanthelium aciculare subsp. fusiforme grows in sandy pine or oak savannahs. It tends to replace subsp. angustifolium from southern Florida through Central America and the Antilles.


Dichanthelium aciculare subsp. neuranthum (Griseb.) Freckmann & Lelong

Plants cespitose. Culms 30-60 cm, stiffly erect, wiry, sparsely pubescent to almost glabrous. Cauline blades erect, narrow, often involute. Primary panicles usually contracted; branches appressed to ascending, appearing 1-sided. Spikelets 2-2.8 mm, ellipsoid.

Dichanthelium aciculare subsp. neuranthum grows in moist, sandy, open ground and savannahs, primarily on the outer coastal plain and in Cuba and various other Caribbean islands.


28.   Dichanthelium consanguineum (Kunth) Gould & C.A. Clark
Kunth's Panicgrass

Plants grayish-green, cespitose. Basal rosettes poorly differentiated; blades 2-8 cm, ovate to lanceolate, grading into the cauline blades. Culms 20-55 cm, erect; nodes densely bearded; internodes densely villous; fall phase with spreading culms branching from the lower and midculm nodes, eventually producing flabellate clusters of reduced, flat blades, secondary panicles much reduced. Cauline leaves 3-4; sheaths shorter than the internodes, pilose with ascending papillose-based hairs to villous; ligules 0.5-2 mm, of hairs; blades 4-12 cm long, 2-8 mm wide, stiffly ascending to erect, often wrinkled along the prominent veins, usually villous on both surfaces, apices involute-pointed, blades of the flag leaves much reduced. Primary panicles 3-7 cm long, 1-4 cm wide, well-exserted; branches usually ascending, glabrous or puberulent. Spikelets 2.3-3 mm long, 1.4-1.8 mm wide, obovoid, biconvex in side view, densely pubescent, attenuate basally. Lower glumes about 1/3 as long as the spikelets, attached about 0.2 mm below the upper glumes, clasping at the base, broadly triangular, thinner than the upper glumes, weakly veined; upper glumes with 5-9 prominent veins; lower florets sterile; upper florets broadly ellipsoid, apices blunt, minutely puberulent. 2n = 18.

Dichanthelium consanguineum grows in sandy woodlands and low, boggy pinelands. It is restricted to the southeastern United States. The primary panicles are open-pollinated and produced from April to June; the secondary panicles are cleistogamous and produced from June into fall. Some specimens of D. consanguineum suggest that hybridization occasionally occurs with D. aciculare or D. ovale.


Dichanthelium sect. Strigosa Freckmann & Lelong

Plants densely cespitose, with caudices. Basal rosettes poorly differentiated; blades scarcely separable from the crowded lower cauline blades. Culms 5-55 cm, slender, erect to spreading, lower internodes short, upper 3-5 internodes elongate; fall phase usually forming a dense cushion. Cauline leaves 2-4; ligules membranous, ciliate; blades soft, green to yellowish, margins usually ciliate. Primary panicles exserted at maturity. Spikelets 1.1-2.3 mm, broadly ellipsoid to obovoid, glabrous or pubescent. Upper florets subacute or minutely umbonate.


29.   Dichanthelium laxiflorum (Lam.) Gould
Soft-Tufted Panicgrass

Plants densely cespitose. Basal rosettes poorly differentiated; blades ovate to lanceolate. Culms 15-55 cm, slender, erect or radiating from a large tuft of predominantly basal leaves, lower internodes short, upper 3-5 internodes elongate; nodes bearded with soft, spreading or retrorse hairs; internodes glabrous; fall phase branching extensively from the basal nodes, forming a dense cushion that overwinters. Cauline leaves 2-4; sheaths usually longer than the internodes, pilose, hairs to 4 mm, retrorse or spreading; ligules 0.2-1 mm, at low magnification appearing to be membranous and ciliate, at high magnification evidently of hairs that are coherent at the base; blades 4-17 cm long, 4-12 mmwide, lanceolate, at least 3/4 as long as the basal blades, spreading to suberect, thin, soft, lax, yellowish-green, nearly glabrous or densely pilose on 1 or both surfaces, margins usually finely short-ciliate, at least on the basal 1/2, cilia not papillose-based. Primary panicles 4-12 cm long, 3-8 cm wide, well-exserted; secondary panicles more compact, usually not exserted above the crowded basal leaves; rachises and branches wiry, spreading or deflexed, often pilose. Spikelets 1.7-2.3 mm long, 1-1.2 mm wide, broadly ovate or oblong-obovoid, with papillose-based hairs, obtuse. Lower glumes 1/4-1/3 as long as the spikelets, broadly deltoid; upper glumes and lower lemmas subequal, usually fully covering the upper florets; upper florets 1.5-1.8 mm long, 1-1.2 mm wide, broadly ellipsoid or obovoid, minutely umbonate. 2n = 18.

Dichanthelium laxiflorum is a widespread, common species that grows in mesic deciduous woods, and occasionally in drier, more open woodlands. Its range extends south from the Flora region into Mexico. The density of the pubescence on the blade surfaces varies greatly.

The primary (spring) panicles are apparently chasmogamous; the secondary panicles are largely cleistogamous and are produced from late spring to winter.


30.   Dichanthelium strigosum (Muhl. ex Elliott) Freckmann
Cushion-Tufted Panicgrass

Plants densely cespitose. Basal rosettes poorly differentiated; blades 1-5 cm, lanceolate, grading into the cauline blades. Culms 5-45 cm, slender, erect or spreading; from a dense tuft of predominantly basal leaves, lower internodes short, upper 3-5 internodes elongate; nodes glabrous or bearded; internodes glabrous or pilose; fall phase with spreading culms and branches arising from near the bases forming a dense, flat tuft. Cauline leaves 2-4; lower cauline sheaths longer than the internodes, mostly glabrous or pilose with ascending hairs, margins finely ciliate; ligules 0.2-2 mm, at low magnification appearing to be membranous and ciliate, at high magnification evidently of hairs that are coherent at the base; blades 1.5-6 cm long, 3-8 mm wide, lanceolate, glabrous or softly pilose, margins with prominent papillose-based cilia, at least basally. Primary panicles short- to long-exserted; rachises and branches often pilose. Spikelets 1.1-2.1 mm, obovoid to broadly ellipsoid, glabrous or pubescent, hairs not papillose-based. Lower glumes 1/3-1/2 as long as the spikelets, acute to obtuse; upper florets 0.8-1.7 mm, ellipsoid, subacute.

Dichanthelium strigosum extends from the southeastern Flora region south into Mexico, the Caribbean, and into northern South America.

The primary panicles are briefly open-pollinated in April or May; the secondary panicles, which are produced from May through November, are cleistogamous. The three subspecies are mostly sympatric and sometimes grow together, with occasional intergradation.

1
Spikelets pubescent, broadlyellipsoid, 1.6-2.1 mm long; lower glumes about 1/2 as long as the spikelets; blades glabrous ..... subsp. leucoblepharis
Spikelets glabrous, obovoid, 1.1-1.8 mm long; lower glumes about 1/3 as long as the spikelets; blades pilose or glabrous (2)
2
Blades pilose; spikelets 1.1-1.6 mm long ..... subsp. strigosum
Blades glabrous or sparsely pilose near the base; spikelets 1.4-1.8 mm long ..... subsp. glabrescens


Dichanthelium strigosum subsp. glabrescens (Griseb.) Freckmann & Lelong

Culms usually less than 30 cm, glabrous, usually very densely cespitose; nodes glabrous. Cauline blades mostly glabrous, sometimes sparsely pilose basally. Spikelets 1.4-1.8 mm, glabrous, obovoid; lower glumes about 1/3 as long as the spikelets. 2n = unknown.

Dichanthelium strigosum subsp. glabrescens grows in sandy, open pine woods and bogs. Its range extends from Mississippi along the coast to Florida and south through the West Indies.


Dichanthelium strigosum subsp. leucoblepharis (Trin.) Freckmann & Lelong

Culms usually 5-30 cm, glabrous or sparsely pubescent; nodes glabrous. Cauline blades glabrous. Spikelets 1.6-2.1 mm, broadly ellipsoid, pubescent; lower glumes about 1/2 as long as the spikelets. 2n = unknown.

Dichanthelium strigosum subsp. leucoblepharis grows in low, moist, sandy pinelands and bogs. Its range extends from North Carolina along the coastal plain to Florida and eastern Texas and into Mexico.


Dichanthelium strigosum (Muhl. ex Elliott) Freckmann subsp. strigosum

Culms often 30-45 cm, pilose to subglabrous; nodes bearded. Cauline blades pilose on both surfaces, those of the upper leaves very reduced. Spikelets 1.1-1.6 mm, glabrous, obovoid; lower glumes about 1/3 as long as the spikelets. 2n = 18.

Dichanthelium strigosum subsp. strigosum grows in sandy, low, open pine woods and bogs. It is the most widespread of the three subspecies, extending from southeastern Virginia through the coastal plain to eastern Texas, Florida, Cuba, and the West Indies to Colombia.


Dichanthelium sect. Linearifolia Freckmann & Lelong

Plants cespitose, with caudices. Basal rosettes poorly differentiated; blades narrow, erect or ascending, resembling the lower cauline blades in shape. Culms 10-50 cm, erect to spreading or drooping, lower internodes very short, upper 2-4 internodes often much elongated; fall phase branching from the basal nodes, usually producing sterile shoots or condensed secondary panicles within about 5 cm of the ground. Cauline leaves 2-4; ligules 0.5-1 mm, of hairs; blades usually erect, stiff, upper blades 1-5 mm wide, 15-60 times as long. Primary panicles usually exserted. Spikelets narrowly ellipsoid to obovoid, usually pubescent, sometimes glabrous. Upper florets subacute to acute or umbonate.


31.   Dichanthelium wilcoxianum (Vasey) Freckmann
Wilcox's Panicgrass

Plants cespitose. Basal rosettes poorly differentiated; sheaths glabrous; blades 2-4 cm, narrow, similar to those of the lower cauline leaves, ascending to spreading. Culms 15-35 cm, stiffly erect, all but the upper 2-4 internodes very short; nodes glabrous or with weak, reflexed hairs; internodes purplish-gray, sparsely pubescent; fall phase developing early, forming erect branches from the lower or midculm nodes, each branch terminating in a partially included panicle of 8-16 spikelets, no sterile shoots formed. Cauline leaves usually 3; sheaths hirsute, hairs papillose-based; ligules 0.5-1 mm; blades 4-8 cm long, 2-5 mm wide, all alike, stiffly erect, green to grayish-green, flat, not plicate, sparsely pilose. Primary panicles 3-5 cm long, 2-4 cm wide, ovoid, open, shortly exserted, with 12-32 spikelets; branches short, stiff, spreading; pedicels mostly 4-8 mm, spreading. Spikelets 2.4-3.2 mm long, 0.7-1.2 mm wide, ellipsoid to obovoid, often reddish throughout, short-pubescent. Lower glumes 0.7-1.2 mm, triangular; upper glumes and lower lemmas about equaling the upper florets; upper florets 1.9-2.5 mm, ellipsoid, pointed. 2n = 18.

Dichanthelium wilcoxianum grows in dry prairies, especially in sandy or gravelly openings. It is restricted to the Flora region. The primary panicles, which are produced from mid-May to early June, are partially open-pollinated; the secondary panicles, which are produced in June, and occasionally also in September, are cleistogamous.

Some specimens of Dichanthelium oligosanthes subsp. scribnerianum from the southern Great Plains that have prematurely elongating upper internodes resemble D. wilcoxianum, but they have greenish spikelets that are 1.7-2.4 mm wide, an orange spot at the base of the glumes, and larger basal rosettes.


32.   Dichanthelium perlongum (Nash) Freckmann
Long-Stalked Panicgrass

Plants densely cespitose. Basal rosettes poorly developed; sheaths 2-4 cm; blades similar in shape to the lower cauline blades, narrow, ascending. Culms 10-50 cm, erect, lower 3-6 internodes telescoped together, forming a slender 2-4 cm column, upper 2 internodes elongated; nodes bearded; internodes puberulent and pubescent; fall phase with sterile branches arising near ground level and foreshortened reproductive branches arising from the higher nodes, secondary panicles small and narrow, enclosed within the sheaths, with 5-10 spikelets. Cauline leaves 2-4; sheaths longer than the internodes, pilose; ligules about 0.5 mm; blades 5-20 cm long, 1-3.5 mm wide, stiffly erect, long-tapering, sometimes involute, green or grayish-green, pubescent to pilose, upper 2 or 3 blades much longer than those below. Primary panicles 3-8 cm long, 1-3 cm wide, narrowly ellipsoid, long-exserted, with 12-25 spikelets; branches ascending; pedicels 2-4 mm, appressed. Spikelets 2.6-3.4 mm long, 1-1.7 mm wide, ellipsoid-obovoid, turgid, finely pubescent. Lower glumes 1-1.4 mm, broadly ovate; upper glumes and lower lemmas exceeding the upper florets by 0.2-0.3 mm before flowering, slightly pointed at maturity, upper florets obovoid, 1.9-2.7 mm, minutely umbonate. 2n = 18.

Dichanthelium perlongum grows in dry to mesic prairies, and is restricted to the Flora region. It appears to hybridize occasionally with D. depauperatum and D. linearifolium. The primary panicles are briefly open-pollinated and develop from May to early June; the secondary panicles are cleistogamous and are produced from mid-June through mid-July.

Dichanthelium perlongum is similar to D. wilcoxianum, but differs in having only the upper 1 or 2 blades greatly elongated (usually more than 20 times longer than wide), narrow, erect basal blades, and a contracted panicle with ascending branches. Dichanthelium acuminatum also may also be confused with D. perlongum only if its upper internodes elongate, as tends to be the case after a spring fire, but D. acuminatum has less turgid spikelets and hairs in the ligule area that are 3-5 mm long.


33.   Dichanthelium linearifolium (Scribn.) Gould
Linear-Leaved Panicgrass, Panic à Feuilles Linéaires

Plants cespitose. Basal rosettes poorly differentiated; blades similar in shape to the lower cauline blades, narrow, ascending. Culms 10-50 cm, very slender, erect to drooping, lower 3-8 internodes telescoped together, less than 2 cm, upper 2 internodes elongated; nodes bearded; internodes pubescent to almost glabrous; fall phase developing a dense mass of erect blades and foreshortened branches arising from the basal nodes, terminating in small, narrow secondary panicles that are enclosed within the sheaths, with 6-15 spikelets. Cauline leaves 2-4; sheaths longer than the internodes, glabrous or pilose with dense, fine, papillose-based hairs; ligules about 0.5 mm; blades 5-20 cm long, 2-5 mm wide, stiffly ascending to erect, green to grayish-green, glabrous or densely pilose, apices long-tapering, lower blades shorter than the upper 2 or 3 blades. Primary panicles 4-10 cm long, 2-6 cm wide, long-exserted, with 12-70 spikelets; branches and pedicels spreading. Spikelets 2-3.2 mm long, 0.8-1.4 mm wide, ellipsoid, not turgid, sparsely pubescent. Lower glumes 0.6-1.1 mm, ovate-triangular; upper glumes and lower lemmas exceeding the upper florets by about 0.2 mm before flowering, subequal in fruit, slightly pointed at maturity, upper florets 1.7-2.3 mm, ovoid-ellipsoid, minutely umbonate. 2n = 18.

Dichanthelium linearifolium grows in dry, open woodlands, rock outcroppings, and sandy areas. It is restricted to the Flora region. The primary panicles are briefly open-pollinated, produced from May to early June; the secondary panicles are cleistogamous, produced from late June through July (rarely in fall). Plants in the northern United States and Canada tend to be shorter and more spreading, subglabrous, and to have spikelets 2-2.6 mm long; they have been called Panicum werneri Scribn., but do not merit taxonomic recognition. In the southwestern part of its range, especially in the Ozarks, most plants of D. linearifolium are tall, erect, densely pilose, with very elongated blades and spikelets often 2.6-3 mm long; they may hybridize with D. perlongum.


34.   Dichanthelium depauperatum (Muhl.) Gould
Starved Panicgrass, Panic Appauvri

Plants cespitose. Basal rosettes poorly differentiated; blades similar in shape to the lower cauline blades, narrow, ascending. Culms 10-45 cm, erect to spreading, lower 4-10 internodes telescoped together, less than 2 cm, upper 2 internodes elongated; nodes bearded; internodes pubescent to subglabrous; fall phase a dense mass of erect blades and foreshortened branches that arise from the basal culm nodes, about 1/2 of the branches sterile, others with small, narrow, secondary panicles of 3-7 spikelets that remain enclosed within the sheaths. Cauline leaves 2-4; sheaths longer than the internodes, glabrous or densely ascending-pilose; ligules about 0.5 mm; blades 6-15 cm long, 1-4 mm wide, green to grayish-green, sometimes involute, glabrous or densely pilose, apices long-tapering, lower blades small to vestigial, upper 2 or 3 blades longer and stiffly erect. Primary panicles 3-6 cm long, 1.5-3 cm wide, usually long-exserted (sometimes contracted and remaining basal), with 7-25 spikelets. Spikelets 3.2-4.3 mm long, 1-1.7 mm wide, ellipsoid-pointed, glabrous or finely pubescent. Lower glumes 1.2-1.6 mm, narrowly triangular; upper glumes and lower lemmas exceeding the upper florets by 0.2-1 mm, forming a pointed beak, upper florets 1.9-3.1 mm, obovoid, minutely umbonate. 2n = 18.

Dichanthelium depauperatum grows in dry, open woodlands and open, disturbed areas, especially on sand. It is restricted to the Flora region. The primary panicles, which are rarely open-pollinated, are produced from May to early June; the secondary, cleistogamous panicles are produced from late June through July (rarely in fall). The species is linked with D. perlongum and D. linearifolium by occasional hybrids and hybrid derivatives. In the northern United States and Canada, 80-90% of the plants are glabrous and have been called Panicum depauperatum var. psilophyllum Fernald, Panicum depauperatum var. involutum (Torr.) Alph. Wood, or, if the primary panicles remain near the base, Panicum depauperatum forma cryptostachys Fernald; in this treatment, none of these are recognized as distinct taxonomic entities. The frequency of pilose plants increases southward, where some populations are entirely pilose.