25.01   DIGITARIA Haller
J.K. Wipff

Plants annual, perennial, or of indefinite duration. Culms 5-250 cm, erect or decumbent, branching basally or at aerial culm nodes, when annual or of indefinite duration usually decumbent and rooting at the lower nodes. Sheaths open; ligules membranous, sometimes ciliate; blades usually flat. Inflorescences terminal, sometimes also axillary, usually panicles of 1-sided spikelike branches (sometimes only 1 branch) attached digitately or racemosely to a rachis, sometimes simple panicles of solitary, pedicellate spikelets; spikelike branches, if present, sometimes with secondary branches, primary branch axes triquetrous, bearing spikelets abaxially, in 2 rows, usually in unequally pedicellate groups of 2-5, occasionally borne singly. Spikelets 1.2-8.2 mm, lanceoloid to ellipsoid, dorsally compressed, apices obtuse to acuminate, unawned, with 2 florets; disarticulation beneath the glumes. Lower glumes absent or to 1/4 as long as the spikelets; upper glumes usually from 1/6 as long as to equaling the spikelets, occasionally absent, 0-5-veined, usually pubescent; lower florets sterile; lower lemmas membranous, usually as long as the upper lemmas, usually pubescent, (3)5-7(13)-veined; lower paleas absent or reduced; upper lemmas mostly stiffly chartaceous to cartilaginous, obscurely veined, with 0.5-1 mm hyaline margins that embrace the upper paleas; upper paleas similar to the upper lemmas in texture and size; lodicules 3, cuneate; anthers 3. Caryopses plano-convex; embryos 1/5-1/2 as long as the caryopses; hila punctiform to ellipsoid. x = 9. Name from the Latin digitus, finger, a reference to the digitate inflorescence of some species.

Digitaria has approximately 200 species and grows primarily in tropical and warm-temperate regions, often in disturbed, open sites. Some species are grown as cereals; others for forage or as lawn grasses. In North America, the genus is best known for two of its weedy species, D. sanguinalis and D. ciliaris. There are 29 species known to occur in the Flora region; 18 are native to the region.

Most annual species of Digitaria will survive several years in regions without a pronounced cold season; such species are described as being of indefinite duration.


SELECTED REFERENCES Boonbundarl, S. 1985. A biosystematic study of the Digitaria leucites complex in North America. Ph.D. dissertation, Texas A&M University, College Station, Texas, U.S.A. 238 pp.; Gould, F.W.1975. The Grasses of Texas. Texas A&M University Press, College Station, Texas, U.S.A. 653 pp.; Henrard, J. 1950. Monograph of the genus Digitaria. Universitaire Pers Leiden, Leiden, The Netherlands. 999 pp.; Kartesz, J. and C.A. Meacham. 1999. Synthesis of the North American Flora, Version 1.0 (CD-ROM). North Carolina Botanical Garden, Chapel Hill, North Carolina, U.S.A.; Kok, P.D.F., P.J. Robbertse, and A.E. van Wyk. 1989. Systematic study of Digitaria section Digitaria (Poaceae) in southern Africa. S. African J. Bot. 55:141-153; Veldkamp, J.F. 1973. A revision of Digitaria in Malesia. Blumea 21:1-80; Webster, R.D. 1981. A biosystematic study of the Digitaria sanguinalis complex in North America (Poaceae). Ph.D. dissertation, Texas A&M University, College Station, Texas. 156 pp.; Webster, R.D. 1983. A revision of the genus Digitaria Haller (Paniceae: Poaceae) in Australia. Brunonia 6:131-216; Webster, R.D. 1987. Taxonomy of Digitaria section Digitaria in North America (Poaceae: Paniceae). Sida 12:209-222; Webster, R.D. and S.L. Hatch. 1981. Taxonomic relationships of Texas specimens of Digitaria ciliaris and Digitaria bicornis (Poaceae). Sida 9:34-42; Webster, R.D. and S.L. Hatch. 1990. Taxonomy of Digitaria section Aequiglumae (Poaceae: Paniceae). Sida 14:145-167; Wipff, J.K. and S.L. Hatch. 1994. A systematic study of Digitaria sect. Pennatae (Poaceae: Paniceae) in the New World. Syst. Bot. 19:613-627.

NOTE: The pubescence of the lower lemmas may be mistaken for two white lines between the veins because the individual hairs are not visible, being both tightly packed and closely appressed.

1
Inflorescences simple open panicles, with well-developed primary and secondary branches; branches and pedicels divergent; spikelets solitary (2)
Inflorescences panicles of spikelike branches; secondary branches rarely present; spikelets appressed to the branches, in groups of 2-5 on the middle portion of the primary branches (5)
2
Upper glumes absent or to 0.6 mm long, veinless ..... 4. D. tomentosa
Upper glumes 1.8-3.8 mm long, 3-7-veined (3)
3
Spikelets 3.5-4.6 mm long; upper glumes 5-7-veined ..... 1. D. arenicola
Spikelets 2.2-3.3 mm long; upper glumes 3(5)-veined (4)
4
Lower lemmas 7-veined, veins not equally spaced ..... 2. D. cognata
Lower lemmas 5-veined, veins equidistant ..... 3. D. pubiflora
5
Spikelets in groups of 3-5 on the middle portions of the primary branches, the longer pedicels in each group often adnate to the branch axes for part of their length (6)
Spikelets paired on the middle portions of the primary branches; pedicels not adnate to the branch axes (17)
6
Upper lemmas pale yellow or gray when immature, light brown to brown when mature, sometimes purple-tinged (7)
Upper lemmas brown when immature, becoming dark brown when mature (9)
7
Upper glumes 1/6-1/3 long as the spikelets; sheaths and blades pubescent ..... 13. D. serotina
Upper glumes equaling or almost equaling the spikelets; sheaths and blades usually glabrous (8)
8
Upper glumes 5-veined; spikelets elliptic to obovate; plants stoloniferous ..... 14. D. longiflora
Upper glumes 3-veined; spikelets lanceolate; plants not stoloniferous ..... 15. D. floridana
9
Primary panicle branches wing-margined, the wings at least 1/2 as wide as the midribs (10)
Primary panicle branches not wing-margined or the wings not as wide as the midribs (12)
10
Plants always with axillary panicles in the lower leaf sheaths, these panicles sometimes completely concealed by the sheaths; spikelets 1.7-2.3 mm long ..... 16. D. ischaemum
Plants without axillary panicles; spikelets 1.2-1.7 mm long (11)
11
Primary panicle branches, if more than 2, racemose, the terminal branches erect, the other branches usually divergent; upper lemmas light brown to brown at maturity; upper glumes almost as long as the upper lemmas ..... 15. D. floridana
Primary panicle branches usually all digitate, sometimes 1 below the others, all the branches erect to ascending; upper lemmas dark brown at maturity; upper glumes 1/2 as long as to almost equaling the upper lemmas ..... 17. D. violascens
12
Lower lemmas pubescent (13)
Lower lemmas glabrous (15)
13
Plants annual, or short-lived perennials, branching at the lower nodes; cauline nodes 3-6 ..... 7. D. filiformis
Plants perennial, not branching at the lower nodes; cauline nodes 1-2 (14)
14
Upper glumes and lower lemmas with long, glandular-tipped hairs along their margins and intercostal regions ..... 8. D. leucocoma
Upper glumes and lower lemmas glabrous over most of their length, sparsely pubescent near the apices, the hairs short, not glandular-tipped ..... 6. D. bakeri
15
Upper glumes less than 1/2 as long as the spikelets ..... 5. D. gracillima
Upper glumes more than 1/2 as long as the spikelets (16)
16
Plants annual, branching at the lower nodes; culm nodes 3-6; upper glumes obtuse ..... 7. D. filiformis
Plants perennial, not branching at the lower nodes; culm nodes 1-2; upper glumes acute ..... 6. D. bakeri
17
Upper lemmas brown when immature, almost always dark brown when mature; primary branches not wing-margined or with wings less than 1/2 as wide as the midribs (18)
Upper lemmas pale yellow, tan, or gray, sometimes purple-tinged, when immature; gray, yellow, tan, light brown, or purple at maturity; primary branches sometimes wing-margined, the margin widths various (23)
18
Spikelets (including pubescence) 1.3-3.1 mm long; lower lemmas (including pubescence) shorter than or no more than 0.5 mm longer than the upper florets; ligules 0.1-1.5 mm long, ciliate; lower lemmas sparsely to densely pubescent, the hairs less than 1 mm long, appressed, not spreading at maturity (19)
Spikelets (including pubescence) 3.7-7.5 mm long; lower lemmas (including pubescence) exceeding the upper florets by 0.8 mm or more; ligules 1-6 mm long, not ciliate; lower lemmas densely pubescent, the hairs 1-6 mm long, usually spreading at maturity (21)
19
Lower glumes 0.3-1 mm long; plants perennial, with hard, knotty, shortly rhizomatous bases; culms erect, not rooting at the lower nodes; lower lemmas 5-veined, the veins equally spaced ..... 9. D. hitchcockii
Lower glumes absent or to 0.1 mm long; plants annual, or short-lived perennials; culms erect or decumbent, sometimes rooting at the lower nodes; lower lemmas 5-7-veined, the veins unequally spaced, the outer veins closely spaced (20)
20
Upper lemmas dark brown at maturity; lower primary panicle branches without secondary branches; upper glumes with clavate to capitate hairs ..... 7. D. filiformis
Upper lemmas usually gray, sometimes brown, at maturity; lower primary panicle branches with strongly divergent secondary branches; upper glumes with tapering or parallel-sided hairs ..... 25. D. velutina
21
Terminal pedicels of primary branches 7.4-20 mm long; primary branches usually divergent, sometimes ascending, at maturity, the middle internodes (4.5)6-15 mm long ..... 10. D. patens
Terminal pedicels of primary branches 1.7-6(7) mm long; primary branches appressed to ascending at maturity, the middle internodes 2-6 mm long (22)
22
Lower lemmas pubescent between most, sometimes all, of the veins and on the margins ..... 12. D. insularis
Lower lemmas glabrous between the veins, pubescent on the margins, sometimes also on the lateral veins ..... 11. D. californica
23
Primary panicle branches not or only narrowly wing-margined, the wings no more than 1/2 as wide as the midribs (24)
Primary branches winged, the wings at least 1/2 wide as the midribs (28)
24
Spikelets 1.5-2.5 mm long (25)
Spikelets 2.5-3.6 mm long (26)
25
Upper glumes glabrous; plants rhizomatous; culms decumbent but usually not rooting at the lower nodes ..... 18. D. abyssinica
Upper glumes shortly villous on the margins, sometimes also elsewhere; plants not rhizomatous; culms erect or decumbent and rooting at the lower nodes ..... 21. D. texana
26
Culms usually branching at the aerial nodes, not rooting at the lower nodes; leaf blades 2-2.2 mm wide, flat or folded; upper glumes glabrous ..... 19. D. pauciflora
Culms not branching at the aerial nodes, often rooting at the lower nodes; leaf blades 2-7mm wide, flat; upper glumes villous or glabrous (27)
27
Upper glumes 7-9-veined, glabrous or obscurely pubescent; plants of indefinite duration ..... 20. D. simpsonii
Upper glumes (3)5-veined, shortly villous on the margins and sometimes between the margins; plants perennial ..... 21. D. texana
28
Plants perennial, usually stoloniferous, sometimes also rhizomatous (29)
Plants annual or of indefinite duration, usually neither rhizomatous nor stoloniferous (31)
29
Leaf blades 1-3 mm wide; panicles with 2-4 primary branches, the branches 2-7 cm long ..... 22. D. didactyla
Leaf blades 3-13 mm wide; panicles with 2-18 primary branches, the branches 5-25 cm long (30)
30
Midveins of the lower lemmas scabrous, at least on the distal 1/2 ..... 24. D. milanjiana
Midveins of the lower lemmas smooth throughout ..... 23. D. eriantha
31
Lateral veins of the lower lemmas scabrous for the distal 2/3 of their length, sometimes scabrous throughout (use 20× magnification); leaf blades usually with papillose-based hairs on both surfaces ..... 28. D. sanguinalis
Lateral veins of the lower lemmas smooth throughout or scabrous only on the distal 1/3; leaf blades with or without papillose-based hairs (32)
32
Lower lemmas of the lower spikelets of each pair 7-veined, the 2 lateral veins on each side crowded together near the margins, the 3 central veins equally spaced (33)
Lower lemmas of the lower spikelets of each pair 5- or 7-veined, the 2 or 3 lateral veins on each side crowded together near the margins, well-separated from the midvein (36)
33
Lower primary panicle branches with strongly divergent secondary branches ..... 25. D. velutina
Lower primary panicle branches without secondary branches (34)
34
Spikelets 2.6-3.7 mm long; spikelets dimorphic with respect to their pubescence; lower lemmas of the upper spikelets of each spikelet pair with marginal hairs that become widely divergent at maturity; lower lemmas of the lower spikelets in each pair glabrous or with hairs that remain appressed at maturity; lowest panicle nodes glabrous or with hairs less than 0.4 mm long ..... 29. D. bicornis
Spikelets 1.7-2.8 mm long; spikelets homomorphic with respect to their pubescence; lowest panicle nodes with hairs more than 0.4 mm long (35)
35
Adaxial surfaces of the blades evenly, sometimes densely, hairy; leaf sheaths usually with scattered hairs; upper glumes 1/3-1/2 as long as the spikelets ..... 26. D. horizontalis
Adaxial surfaces of the blades glabrous or with a few long hairs near the base; leaf sheaths glabrous or with a few long hairs near the base; upper glumes 2/5-4/5 as long as the spikelets ..... 27. D. nuda
36
Lower glumes absent or no more than 0.1 mm long (37)
Lower glumes 0.1-0.8 mm long (38)
37
Anthers 0.6-1.3 mm long; upper glumes 0.2-1.3 mm long, less than 0.4 times as long as the spikelets ..... 31. D. setigera
Anthers 0.3-0.6 mm; upper glumes 1-2.2 mm long, 0.4-0.8 times as long as the spikelets ..... 27. D. nuda
38
Lower glumes 0.2-0.8 mm long; primary branches glabrous or with hairs shorter than 1 mm; spikelets 2.7-4.1 mm long ..... 30. D. ciliaris
Lower glumes 0.1-0.2 mm long; primary branches often with scattered hairs 1-4 mm long; spikelets 1.7-2.8 mm long (39)
39
Adaxial surfaces of the blades evenly hairy, sometimes densely so; leaf sheaths usually with scattered hairs; upper glumes 0.3-0.5 times as long as the spikelets ..... 26. D. horizontalis
Adaxial surfaces of the blades glabrous or with a few long hairs near the base; leaf sheaths glabrous or with a few long hairs near the base; upper glumes 0.4-0.8 as long as the spikelets ..... 27. D. nuda


1.   Digitaria arenicola (Swallen) Beetle
Sand Witchgrass

Plants perennial; loosely tufted, with long, creeping rhizomes. Culms 20-60 cm, erect; lower nodes glabrous or pubescent; upper nodes glabrous. Leaves mainly cauline; sheaths usually glabrous, lower sheaths sometimes pubescent; ligules 0.4-1 mm, truncate, entire to lacerate; blades 5-11.5 cm long, 3-4.5 mm wide, glabrous, usually flat or folded. Panicles simple, 12-24 cm long, 19-40 cm wide, open; nodes hispid; branches divergent; lower primary branches 10-21 cm, with 1-several sterile branches near the base; pedicels divergent, spikelets solitary. Spikelets 3.5-4.6 mm long, 0.8-1 mm wide, elliptical. Lower glumes 0.2-0.5 mm; upper glumes 3-3.8 mm, 5-7-veined, densely villous between the veins, hairs white, becoming purple at maturity; lower lemmas similar to the upper glumes in size, texture, and pubescence; upper lemmas 3-3.7 mm, narrowly acute, dark brown; anthers 1.1-1.4 mm. Caryopses 1.5-2 mm. 2n = 36, 37.

Digitaria arenicola is endemic to deep sands along the coast of Texas, a very restricted habitat and one that is being lost to the development of coastal parks and housing.


2.   Digitaria cognata (Schult.) Pilg
Fall Witchgrass

Plants perennial; cespitose, without rhizomes. Culms 30-56 cm, erect; nodes glabrous. Leaves mainly cauline; sheaths glabrous or sparsely to densely pubescent, sometimes with papillose-based hairs; ligules 0.2-1.5 mm, entire to lacerate; blades 2.4-12.6 cm long, 2-5.4 mm wide, glabrous or pubescent. Panicles simple, 12.8-27.5 cm long, 16.5-44.5 cm wide, open; branches divergent; lower primary branches 10.5-24 cm, often with 1-several sterile branches near the base; pedicels divergent, spikelets solitary. Spikelets 2.2-3.1 mm long, 0.7-1.1 mm wide, obovate or broadly elliptic. Lower glumes 0.1-0.8 mm; upper glumes 1.8-2.8 mm, 3(5)-veined, glabrous or pubescent between the veins, hairs appearing as a narrow stripe; lower lemmas similar to the upper glumes in length, texture, and pubescence, 7-veined, veins unequally spaced, lateral veins closer together than the 3 central veins; upper lemmas 1.9-2.9 mm, glabrous, dark brown, narrowly acute; anthers 0.5-0.7 mm, yellow or purple. Caryopses 1.3-1.6 mm. 2n = 36.

Digitaria cognata grows in dry, sandy soils in the eastern portion of the Flora region, from southern Ontario and Vermont through the United States and thence to southern Mexico.


3.   Digitaria pubiflora (Vasey) Wipff
Western Witchgrass

Plants perennial; cespitose, with or without rhizomes. Culms 20-70 cm, erect; nodes glabrous or pubescent . Leaves mainly cauline; sheaths glabrous or sparsely to densely pubescent, sometimes with papillose-based hairs; ligules 0.5-2.2 mm, entire to lacerate; blades 1.3-7.7 cm long, 1.5-4.7 mm wide, glabrous or sparsely to densely pubescent. Panicles simple, 4.5-20 cm long, 5.5-31 cm wide, open; branches divergent; lower primary branches 3.6-17.7 cm, often with 1-several sterile branches near the base; pedicels divergent, spikelets solitary. Spikelets 2.3-3.3 mm long, 0.6-1 mm wide, narrowly elliptic. Lower glumes 0.1-0.4 mm; upper glumes 1.8-2.9 mm, 3-veined, densely pubescent between the veins, hairs white, becoming purple at maturity; lower lemmas similar to the upper glumes in length, texture, and pubescence, 5-veined, veins equidistant; upper lemmas 1.9-2.6 mm, glabrous, dark brown, narrowly acute; anthers 0.3-0.5 mm, yellow, red, or purple. Caryopses 1.3-1.6 mm. 2n = 36 or (more commonly) 72.

Digitaria pubiflora grows in dry, sandy or rocky soils from Arizona to central Texas and south to central Mexico.


4.   Digitaria tomentosa (J. König ex Rottler) Henrard

Plants perennial; cespitose, not rhizomatous. Culms 40-90 cm, erect, geniculate. Lower sheaths densely villous; upper sheaths with scattered papillose-based hairs; ligules 1.5-3 mm; blades 4-7(12) cm long, 3-5 mm wide, villous to nearly glabrous, usually sparsely hairy near the ligules. Panicles simple, 10-18 cm, open; branches divergent; pedicels 0.4-3 mm, divergent, spikelets solitary. Spikelets 2-2.5 mm, elliptical, apiculate. Lower glumes absent or to 0.2 mm; upper glumes absent or to 0.6 mm, veinless; lower lemmas as long as the spikelets, 5-veined, margins and intercostal regions more or less pubescent; upper lemmas minutely rugose, dark brown. 2n = 36.

A native of southern India and Ceylon, Digitaria tomentosa is a noxious weed that is not known to occur in the Flora region. It is included here to help ensure that any introduction is correctly identified.


5.   Digitaria gracillima (Scribn.) Fernald

Plants perennial; in dense tufts, not rhizomatous. Culms 60-100 cm, erect. Sheaths villous, particularly the lower sheaths; ligules 0.2-0.4, fimbriate; blades to 47 cm long, 1-2.1 mm wide, involute, glabrous and smooth abaxially, scabrous adaxially, sometimes with a few long hairs near the base. Panicles of 2-3(5) spikelike primary branches on elongate rachises; primary branches 8-13(20) cm, narrowly winged, wings no more than 1/2 as wide as the midribs, with spikelets in unequally pedicellate groups of 3-4(5); secondary branches rarely present; longest pedicels to 5 mm. Spikelets 1.7-2.3 mm, elliptical, glabrous. Lower glumes absent; upper glumes 0.9-1 mm, less than 1/2 as long as the spikelets, 3-veined, glabrous, broadly rounded to truncate; lower lemmas slightly shorter than the spikelets, 5-veined, glabrous; upper lemmas smooth, brown when immature, dark brown at maturity. 2n = unknown.

Digitaria gracillima is a rare species, endemic to scrub and dry pinelands of peninsular Florida. It used to be interpreted as including D. bakeri, but differs from that species both morphologically and ecologically.


6.   Digitaria bakeri (Nash) Fernald

Plants perennial; cespitose. Culms 40-90 cm, erect, unbranched, glabrous; nodes 1-2. Sheaths densely hairy, hairs papillose-based; ligules 0.8-2.2 mm; blades 10-24 cm long, 2-4.5 mm wide, with papillose-based hairs. Panicles with 2-3 spikelike primary branches on 4-7 mm rachises; secondary branches rarely present; primary branches (5)10-22 cm, axes 0.5-0.6 mm wide, not wing-margined, middle portions of the branches with spikelets in groups of 3; pedicels appressed to the axes. Spikelets 2.3-2.4 mm, lanceolate to oblanceolate-elliptic; lower glumes absent; upper glumes1.4-1.5 mm, more than 1/2 as long as the spikelets, 3-veined, truncate to acute, mostly glabrous, apices sparsely hairy; lower lemmas about as long as the spikelets, 7-veined, mostly glabrous, apices sparsely hairy; upper lemmas 2.3-2.4 mm, dark brown to black, apiculate; anthers 1-1.1 mm. 2n = unknown.

Digitaria bakeri grows in pastures, particularly horse pastures, from Florida through Mexico to Panama. It has been treated until recently as a synonym of D. gracillima, but differs from that species both morphologically and ecologically. It is probably more widespread in Florida than the map suggests but, because of its inclusion in D. gracillima, little information is available at present.


7.   Digitaria filiformis (L.) Koeler
Slender Crabgrass

Plants annual, or short-lived perennials; cespitose, not rhizomatous. Culms (10)25-150 cm, erect or decumbent, branching, sometimes rooting at the lower nodes; nodes 3-6. Sheaths keeled, basal sheaths usually with papillose-based hairs, rarely glabrous; ligules 0.3-1.5 mm; blades 2-18 cm long, 1-6 mm wide, flat or involute, glabrous, scabrous, or pilose. Panicles with 2-7 spikelike primary branches, these digitate or the rachises to 1 cm; longest primary branches 3-25 cm long, 0.2-0.4 mm wide, axes triquetrous, not wing-margined, with spikelets in groups of 2-5 on the lower and middle portions. Spikelets 1.3-2.8 mm. Lower glumes absent or to 0.1 mm; upper glumes 1-2 mm long, from 3/4 to almost as long as the spikelets, almost glabrous or sparsely to densely pubescent with clavate to capitate hairs (use 20× magnification), glume apices rounded; lower lemmas equaling the spikelets, glabrous or glandular-pubescent, 5-7-veined, veins unequally spaced, outer 3 veins on each side closer to each other than the midvein is to the inner lateral veins; upper lemmas 1.3-2 mm, apiculate, dark brown at maturity; anthers 0.3-0.6 mm. 2n = 36, 54.

Digitaria filiformis grows throughout the warmer parts of the eastern United States. Digitaria filiformis var. filiformis, the most widespread of its varieties, extending into Mexico.

1
Lower lemmas glabrous ..... var. laeviglumis
Lower lemmas pubescent (2)
2
Basal leaf sheaths glabrous; cauline blades about 1 mm wide, folded or involute ..... var. dolichophylla
Basal leaf sheaths with papillose-based hairs; cauline blades 1-6 mm wide, flat (3)
3
Spikelets 1.3-1.9 mm long; panicle branches 3-13 cm long; culms 10-80 cm tall ..... var. filiformis
Spikelets 2-2.8 mm long; panicle branches 10-25 cm long; plants 75-150 cm tall ..... var. villosa


Digitaria filiformis var. dolichophylla (Henrard) Wipff

Culms 50-115 cm. Basal leaf sheaths glabrous; cauline leaf blades about 1 mm wide, usually involute. Spikelets 1.5-1.6 mm; lower lemmas pubescent.

Digitaria filiformis var. dolichophylla is an uncommon species of moist pine barrens and open ground in southern Florida.


Digitaria filiformis (L.) Koeler var. filiformis

Culms 10-80 cm. Basal leaf sheaths with papillose-based hairs; cauline leaf blades 1-6 mm wide, flat. Panicle branches 3-13 cm. Spikelets 1.3-1.9 mm; lower lemmas pubescent.

Digitaria filiformis var. filiformis is a weed of sandy fields and open, disturbed ground in the southeastern United States and Mexico.


Digitaria filiformis var. laeviglumis (Fernald) Wipff

Culms 75-150 cm. Basal leaf sheaths with papillose-based hairs or glabrous; blades 1-6 mm, flat. Spikelets 1.8-2.5 mm; lower lemmas glabrous.

Digitaria filiformis var. laeviglumis is endemic to sandy soils in New England.


Digitaria filiformis var. villosa (Walter) Fernald

Culms 75-150 cm. Basal leaf sheaths with papillose-based hairs; cauline leaf blades 1-6 mm wide, flat. Panicle branches 10-25 cm. Spikelets 2-2.8 mm; lower lemmas pubescent.

Digitaria filiformis var. villosa has essentially the same geographic range as var. filiformis and grows in similar habitats. Further study may show that the two varieties should be combined.


8.   Digitaria leucocoma (Nash) Urb.

Plants perennial; cespitose. Culmsto 100 cm, erect, not branching at the lower nodes; nodes 1-2. Sheaths with appressed hairs, lower sheaths densely hairy, upper sheaths sparingly hairy near the base, otherwise glabrous; ligules 2-3 mm; blades 10-40 cm long, to 3 mm wide, usually flat, involute when dry. Panicles with 2-4 spikelike branches on 4-6 cm rachises; primary branches 20-25 cm, axes triquetrous, not winged, with spikelets in unequally pedicellate groups of 3(-5) on the basal 1/2; secondary branches rarely present, longer pedicels often adnate to the branch axes basally. Spikelets 2.2-2.5 mm long, 0.8 mm wide, elliptic, acute. Lower glumes absent; upper glumes 3-veined, margins and intercostal regions with long, glandular-tipped hairs; lower lemmas 7-veined, margins and the region between the 2 inner marginal veins with long glandular hairs; upper lemmas light to dark brown at maturity, striate, apiculate. 2n = unknown.

Digitaria leucocoma is known only from high pinelands near Lake Ella, Lake County, Florida. It has been treated in the past as a synonym of D. filiformis var. villosa.


9.   Digitaria hitchcockii (Chase) Stuck.

Plants perennial; rhizomatous, rhizomes short, giving the plants hard, knotty, much-branched bases. Culms 20-55 cm, erect, sometimes geniculate, not rooting at the lower nodes. Basal sheaths tomentose; culm sheaths glabrous or variously pubescent (puberulent, ciliate, or sparsely hirsute); ligules (0.1)0.5-1(1.5) mm, ciliate; blades 2-5.5 cm long, 2-3 mm wide. Panicles with 3-6 spikelike primary branches on 6-10(15) cm rachises; primary branches 1-6 cm, not or only narrowly winged, with spikelets in unequally pedicellate pairs, pedicels not adnate to the branch axes; shorter pedicels 1.5-2 mm; longer pedicels 3-4 mm. Spikelets homomorphic, 2.5-3.1 mm (including pubescence), 2.4-3 mm (excluding pubescence). Lower glumes 0.3-1 mm, veinless; upper glumes 2.1-3 mm (including pubescence), as long as or exceeding the upper florets by no more than 0.5 mm, 3-veined, densely appressed-pubescent, hairs 0.5-1 mm, white to purple, tapering or parallel-sided, not spreading at maturity; lower lemmas 2.3-3.1 mm (including pubescence), as long as or exceeding the upper lemmas by up to 0.5 mm, 5-veined, veins equally spaced, intercostal regions densely appressed-pubescent, hairs 0.5-1 mm, white to purple, tapering or parallel-sided, not spreading at maturity; upper lemmas 2.2-2.5 mm, brown when immature, dark brown at maturity. Caryopses 2.1-3.4 mm. 2n = 36.

Digitaria hitchcockii is an uncommon species of open, dry, gravelly slopes in southwestern Texas and northern Mexico.


10.   Digitaria patens (Swallen) Henrard

Plants perennial; cespitose, neither rhizomatous nor stoloniferous. Culms 40-90 cm, erect, sometimes geniculate, not rooting, at the lower nodes. Leaves mainly cauline; basal sheaths villous; upper sheaths glabrous or sparsely to densely hirsute, hairs papillose-based; ligules (1)1.5-4 mm, entire to lacerate; blades 5-15 cm long, 1-4 mm wide, glabrous or sparsely pubescent. Panicles with 4-10 spikelike primary branches on (4)10-18 cm rachises; primary branches 4-10 cm, usually divergent at maturity, varying to ascending, axes not wing-margined, with spikelets in unequally pedicellate pairs; internodes (4.5)6-15 mm (mid branch); secondary branches rarely present; shorter pedicels 2-2.5 mm; longer pedicels 7-8 mm; terminal pedicels of primary branches 7.4-20 mm. Spikelets homomorphic, 3.7-5.8 mm (including pubescence), 2.9-4.3 mm (excluding pubescence). Lower glumes 0.3-0.5 mm; upper glumes 2.4-3.5 mm (excluding pubescence), 3-veined, densely villous, hairs 1.5-4 mm, silvery-white to purple, spreading at maturity; lower lemmas 2.8-4.2 mm (excluding pubescence), exceeding the upper lemmas by 0.8-2.2 mm, 5-veined and the veins equally spaced or 7-veined and the lateral veins closer to each other than to the central vein, margins densely villous, hairs 1.5-4 mm, silvery-white to purple, spreading at maturity, apices acuminate; upper lemmas 2.6-3.2 mm, lanceolate, brown when immature, dark brown at maturity, acuminate. 2n = 72.

Digitaria patens is endemic to southwestern and southern Texas and adjacent Mexico. It grows in well-drained, usually sandy soils, often in disturbed habitats. Gould (1975) suggested that it might be an octoploid derivative of D. californica.


11.   Digitaria californica (Benth.) Henrard

Plants perennial; cespitose, neither rhizomatous nor stoloniferous. Culms 40-100 cm, erect, sometimes geniculate, not rooting, at the lower nodes. Basal sheaths villous; upper sheaths glabrous, densely villous or densely tomentose, or sparsely to densely hairy, with papillose-based hairs; ligules (1)1.5-6 mm, entire or lacerate, not ciliate; blades 2-12(18) cm long, 2-5(7) mm wide, glabrous or the adaxial surfaces sparsely to densely villous or tomentose. Panicles with 4-10 spikelike primary branches on 5-10 cm rachises, rarely with secondary branches; primary branches 3-6 cm, appressed to ascending, axes not wing-margined; internodes 2-5.5 mm (mid branch), with spikelets in unequally pedicellate pairs;secondary branches rarely present; pedicels not adnate to the branch axes; shorter pedicels 0.1-0.3 mm; longer pedicels 1-2 mm; terminal pedicels of branches 1.7-6(7) mm. Spikelets homomorphic, (3.7)4-7.5 mm (including pubescence), 3-5.4 mm (excluding pubescence). Lower glumes 0.4-0.6 mm; upper glumes 2.5-5.1 mm (excluding pubescence), narrower than the upper florets, 3-veined, densely villous, hairs 1.5-5 mm, silvery-white to purple, widely divergent at maturity; lower lemmas 2.7-5 mm (excluding pubescence), pubescence exceeding the upper florets by 2.2-4 mm, 7-veined, veins unequally spaced, only the 3 or 5 central veins visible, margins and outer lateral veins densely pubescent, hairs 1.5-5 mm, silvery-white to purple, widely divergent at maturity, intercostal regions glabrous, apices attenuate (acuminate); upper lemmas 2.5-3.4 mm, ovate-lanceolate, brown to dark brown, acuminate. Caryopses 1.3-2 mm. 2n = 36, 54, 70, 72.

Digitaria californica grows on plains and open ground from Arizona, southern Colorado, and Oklahoma through Mexico and Central America to South America. The name reflects the fact that the first collection was made in Baja California, Mexico. Plants in the Flora region belong to D. californica (Benth.) Henrard var. californica. They differ from those of D. californica var. villosissima Henrard in having densely villous, rather than densely tomentose, leaves.


12.   Digitaria insularis (L.) Mez ex Ekman

Plants perennial; cespitose, shortly rhizomatous, with knotty bases. Culms 80-130 cm, erect, with densely villous cataphylls, branching from the lower and middle nodes. Sheaths usually sparsely to densely papillose-hirsute, occasionally glabrous; ligules 4-6 mm, usually lacerate, not ciliate; blades 20-50 cm long, 10-17 mm wide, lax, smooth or scabridulous abaxially, scabridulous to scabrous adaxially. Panicles 20-35 cm long, 2-10 cm wide, with numerous spikelike primary branches; primary branches 10-15 cm, appressed to ascending at maturity, axes not wing-margined or with wings less than 1/2 as wide as the midribs; internodes 3-4.5(6) mm (mid branch), with spikelets in unequally pedicellate pairs; secondary branches rarely present; pedicels not adnate to the branches; shorter pedicels 0.7-2 mm; longer pedicels 2.5-5 mm; terminal pedicels 2-5 mm. Spikelets 5.5-8.2 mm (including pubescence), 4.2-5.9 mm (excluding pubescence), narrowly ovate, acuminate. Lower glumes 0.6-0.8 mm; upper glumes 3.5-4.5 mm, 3-5-veined, pubescent on the margins; lower lemmas 4.1-5.7 mm (exceeded 1.5-5 mm by pubescence), narrowly ovate, 7-veined, pubescent between most, sometimes all, of the veins and on the margins, veins usually obscured by a dense covering of golden-brown hairs, hairs 3-6 mm, spreading at maturity, intercostal regions on either side of the midvein glabrous or pubescent with shorter, fine, white hairs, sometimes intermixed with the golden-brown hairs; upper lemmas 3.2-4.5 mm, narrowly ovate, brown when immature, dark brown at maturity, acuminate; anthers 1-1.2 mm. 2n = 36.

Digitaria insularis grows in low, open ground of the southern United States, and extends to the West Indies, Mexico, and through Central America to Argentina.


13.   Digitaria serotina (Walter) Michx.

Plants annual; often mat-forming. Culms 10-30 cm, decumbent and rooting at the lower nodes. Sheaths conspicuously and densely hairy, longer hairs 1.5-2.5 mm, papillose-based, shorter hairs about 0.5 mm, not papillose-based; ligules 1.5-2.5 mm; blades 2-9 cm long, 3-8 mm wide, conspicuously hairy on both surfaces, longer hairs 1.5-2.5 mm, papillose-based, shorter hairs about 0.5 mm, not papillose-based. Panicles with 2-9 spikelike primary branches, digitate or on rachises to 4 cm; primary branch axes 3-10 cm, wing-margined, wings wider than the midribs, lower and middle portions with spikelets in groups of 3; secondary branches rarely present; shortest pedicels 0.5-0.8 mm; midlength pedicels 1.5-2 mm; longest pedicels 3-3.5 mm, adnate to the branch axes basally. Spikelets homomorphic, 1.5-1.8 mm, lanceolate. Lower glumes absent; upper glumes 1/6-1/3 as long as the spikelets, margins and apices with appressed white hairs, hairs about 0.3 mm; lower lemmas 7-veined, veins equally spaced, appressed-pubescent between the inner lateral veins and on the margins, hairs 0.3-0.5 mm, minutely verrucose (use 50× magnification); upper lemmas yellow or tan at maturity. 2n = unknown.

Digitaria serotina is native to the coastal plain of the southeastern United States. It has also been found in Cuba, possibly as an introduction, and on a ballast dump in Philadelphia, Pennsylvania. Its densely hairy sheath and short, densely hairy blades make this one of the more distinctive species of Digitaria in the Flora region.


14.   Digitaria longiflora (Retz.) Pers.

Plants of indefinite duration; stoloniferous, stolons long and branching. Culms 10-60 cm, occasionally branching from the lower nodes. Leaves 3-4, clustered near the base; sheaths usually glabrous; ligules 0.5-1 mm; blades 1.5-4 cm long, 3-5 mm wide, mostly glabrous, bases subcordate and ciliate, with 0.6-1 mm papillose-based hairs. Panicles with 2(-4) spikelike primary branches, digitate; primary branches 2-5 cm, strongly divergent; branch axesabout 1 mm wide, wing-margined, wings wider than the central midribs, with spikelets in unequally pedicellate groups of 3; secondary branches rarely present; shortest pedicels about 0.3 mm; middle pedicels about 1 mm; longest pedicels 1.5-2 mm, adnate to the branch axes basally; axillary panicles not present. Spikelets 1.2-1.5 mm, elliptic or slightly obovate, acute. Lower glumes absent; upper glumes equaling or almost equaling the spikelets, 5-veined, minutely pubescent between the veins and on the margins; lower lemmas subequal to the upper glumes, 7-veined, usually pubescent on the margins and lateral veins, occasionally glabrous, hairs, if present, 0.2-0.4 mm; upper lemmas about 1.2 mm, pale brown or pale gray, becoming light brown at maturity, acute; anthers 0.8-0.8 mm. 2n = 18.

Digitaria longiflora is native to Africa and Asia. It is now established in disturbed areas of Florida, growing on railroad grades and in pastures and lawns.

The illustration of Digitaria longiflora was inadvertently based on a misidentified specimen of D. fulvescens (J. Presl) Henrard. The two species differ in little more than the pubescence of their lemmas, D. longiflora having pubescent lemmas and D. fulvescens glabrous lemmas (G. Davidse, pers. comm.). They should, perhaps, be considered a single species (J. Wipff, pers. comm.). If they are treated as a single species, the correct name for the species is D. longiflora. [Note added by M.E. Barkworth, June 18, 2005.]


15.   Digitaria floridana Hitchc.

Plants annual or of indefinite duration; not stoloniferous. Culms 20-30 cm, decumbent and rooting at the nodes; nodes glabrous. Sheaths mostly glabrous, throats with papillose-based hairs; blades 4-7 cm long, 3-6 mm wide, glabrous. Panicles with 2-4 spikelike primary branches, if more than 2, rachises 7-20 mm and the branches racemose; primary branches 3-6 cm, terminal branch erect, the other(s) usually divergent, axes wing-margined, wings wider than the midribs, with spikelets in unequally pedicellate groups of 3 on the basal and mid-portions; secondary branches rarely present; shortest pedicels about 0.05 mm; middle pedicels about 0.1 mm; longest pedicels 0.2-0.3 mm, adnate to the branch axes basally; axillary panicles not present. Spikelets homomorphic, 1.5-1.7 mm, lanceolate. Lower glumes absent; upper glumes almost equaling the upper lemmas, conspicuously 3-veined; lower lemmas slightly longer than the upper lemmas, 7-veined, veins unequally spaced, all the intercostal regions sparsely hairy, hairs about 0.3 mm; upper lemma slight brown when immature, dark brown at maturity. 2n = unknown.

Digitaria floridana is a rare species that is known only from sandy pine woods in Hernando County, Florida.


16.   Digitaria ischaemum (Schreb.) Muhl.
Smooth Crabgrass, Digitaire Astringente

Plants annual or of indefinite duration. Culms 20-55(70) cm, decumbent, branching and rooting at the lower nodes; nodes 3-4. Sheaths glabrous or sparsely pubescent; ligules 0.6-2.5 mm; blades 1.5-9 cm long, 3-5 mm wide, glabrous, with a few papillose-based hairs basally. Panicles terminal and axillary; terminal panicles with 2-7 spikelike primary branches, subdigitate or on 0.5-2 cm rachises; primary branches 6-15.5 cm, axes wing-margined, wings at least 1/2 as wide as the midribs, with spikelets in groups of 3, lower portions of the longer pedicels adnate to the axes; secondary branches rarely present; axillary inflorescences always present in some of the lower sheaths, entirely or partially concealed. Spikelets 1.7-2.3 mm, homomorphic, narrowly elliptic. Lower glumes absent or a veinless, membranous rim; upper glumes 1.3-2.3 mm, from 3/4 as long as to equaling the upper lemmas, appressed-pubescent; lower lemmas 1.7-2.3 mm, 7-veined, veins unequally spaced, smooth, pubescent; upper lemmas dark brown at maturity; anthers 0.4-0.6 mm. 2n = 36.

Digitaria ischaemum is a Eurasian weed that is now common in lawns, gardens, fields, and waste ground in warm-temperate regions throughout the world, including much of the Flora region. Larger plants with 5-7 inflorescence branches 8-15 cm long have been called D. ischaemum var. mississippiensis (Gatt.) Fernald, but they intergrade with more typical plants, and so do not merit taxonomic recognition.


17.   Digitaria violascens Link

Plants annual or of indefinite duration. Culms 15-60 cm, erect, usually not branching from the upper nodes; nodes 3-4. Sheaths glabrous or sparsely pubescent; ligules 0.6-2.5 mm; blades 1.5-9 cm long, 3-5 mm wide, glabrous, with papillose-based hairs basally. Panicles with 2-7 spikelike primary branches in 1-2 verticils; primary branches 3-12 cm, erect to ascending, axes 0.6-1 mm wide, wing-margined, wings at least 1/2 as wide as the midribs, lower and middle portions of the branches with spikelets in groups of 3(4, 5); secondary branches rarely present; axillary inflorescences absent. Spikelets 1.2-1.7 mm, homomorphic, narrowly elliptic. Lower glumes absent or a veinless, membranous rim; upper glumes 1.2-1.4 mm, 1/2 as long as to almost equaling the upper lemmas, 3-veined, appressed-pubescent, hairs minutely verrucose; lower lemmas 1.2-1.7 mm, 5-7-veined, veins equally spaced, region between the 2 inner lateral veins and the margins appressed-pubescent, hairs 0.3-0.5 mm, smooth or minutely verrucose (use 50× magnification), verrucose hairs most abundant near the lemma bases; upper lemmas light brown when immature, dark brown at maturity; anthers 0.4-0.6 mm. 2n = 36.

Digitaria violascens is a weedy species that is native to tropical regions of the Eastern Hemisphere. It is now established in the Flora region, primarily in the southeastern United States, and in Mexico and Central America. It grows in disturbed sites.


18.   Digitaria abyssinica (Hochst. ex A. Rich.) Stapf

Plants perennial; rhizomatous, mat-forming. Culms 5-80 cm, decumbent, occasionally rooting at the lower nodes, branching freely at the base, erect portion 20-40 cm; nodes 2-6. Sheaths of midculm leaves glabrous or hirsute, with papillose-based hairs; ligules 0.8-2.1 mm; blades 4-15 cm long, 3-10 mm wide, glabrous or sparsely pubescent with papillose-based hairs. Panicles with 2-25 spikelike primary branches on 1-9 cm rachises; primary branches 2-11 cm, axes not winged or narrowly winged, wings less than 1/2 as wide as the midribs, with spikelets in unequally pedicellate pairs; secondary branches rarely present; pedicels not adnate to the branch axes. Spikelets 1.5-2.5 mm long, 0.8-0.95 mm wide, ovate-elliptic to broadly elliptic, usually plump, usually purple-tinged. Lower glumes absent or to 0.8 mm and acute; upper glumes 1.2-2.4 mm, from 0.8 times as long as to almost equaling the spikelets, glabrous, 3-7-veined, veins usually prominent; lower lemmas 1.5-2.5 mm, usually glabrous, occasionally obscurely puberulent on the margins or, very rarely, distinctly pubescent, 7-veined, veins usually prominent; upper lemmas light brown, gray, and purple. 2n = 36.

Introduced from Africa, Digitaria abyssinica is not known to be established in the Flora region, although it has occasionally been cultivated in the southern United States. It is considered a potentially serious weed threat by the U.S. Department of Agriculture.


19.   Digitaria pauciflora Hitchc.

Plants perennial; not rhizomatous. Culms 50-100 cm, erect to somewhat decumbent, not rooting at the lower nodes, usually branching at the aerial nodes. Sheaths grayish-villous; ligules 1.5-2 mm; blades to 12 cm long, 2-2.2 mm wide, flat or folded, densely grayish-villous on both surfaces. Panicles with 2-3 spikelike primary branches, secondary branches not present; primary branches 5-11 cm, axes not winged, without spikelets or with widely spaced abortive spikelets on the proximal 1-1.5 cm, with spikelets in unequally pedicellate pairs at midlength; shorter pedicels about 2 mm; longer pedicels about 3 mm, not adnate to the branch axes. Spikelets 2.7-3.2 mm, appressed, glabrous. Lower glumes minute, rounded, erose; upper glumes slightly shorter than the spikelets, 3-veined, glabrous; lower lemmas7-veined, glabrous; upper lemmas gray or yellow when immature, becoming purple at maturity. 2n = unknown.

Digitaria pauciflora is known only from the type collection, which was collected in pinelands of Dade County, Florida.


20.   Digitaria simpsonii (Vasey) Fernald

Plants of indefinite duration; not rhizomatous. Culms 80-120 cm, erect or decumbent and rooting at the lower nodes, not branching at the aerial nodes. Sheaths hirsute, with papillose-based hairs, those of the innovation sheaths compressed-keeled; ligules 1-2 mm; blades 7-30 cm long, 3-5 mm wide, flat, pilose above and below. Panicles with 6-8 spikelike primary branches on 4-6 cm rachises; primary branches 8-13 cm, axes triquetrous, narrowly winged, wings less than 1/2 as wide as the midribs, lower and middle portions of the branches with spikelets in appressed, unequally pedicellate pairs; secondary branches rarely present; axillary inflorescences not present; pedicels not adnate to the branch axes. Spikelets about 3 mm, elliptic lanceolate, acute. Lower glumes absent or minute and hyaline; upper glumes 7-9-veined, glabrous or obscurely pubescent; lower lemmas 7-9-veined, glabrous or obscurely pubescent; upper lemmas elliptic, yellow or gray, becoming purple at maturity, slightly apiculate. 2n = unknown.

Digitaria simpsonii is a rare species, known only from sandy fields in Florida.


21.   Digitaria texana Hitchc.

Plants perennial; not rhizomatous. Culms 30-80 cm, sometimes erect, usually decumbent and branching and rooting at the lower nodes, not branching at the upper nodes. Sheaths of the lower leaves villous, those of the upper leaves sometimes glabrous, those ofthe flag leaves without axillary panicles; ligules 1.5-2 mm; blades 10-15 cm long, 2-7 mm wide, hirsute to nearly glabrous. Panicles with 5-10 spikelike primary branches on 1-4 cm rachises; primary branches 5-10(13) cm, axes triquetrous, narrowly winged, wings less than 1/2 as wide as the midribs, lower and middle portions of the branches with paired spikelets; secondary branches rarely present. Spikelets 2-3.6 mm, narrowly ovate-oblong, acute. Lower glumes absent; upper glumes almost as long as the spikelets, 3(5)-veined, shortly villous on the margins and sometimes between the margins; lower lemmas similar to the upper glumes; upper lemmas gray or yellow, sometimes purple-tinged, becoming purple at maturity. Caryopses narrowly oblong. 2n = 54.

Digitaria texana grows in sandy oak woods and prairies of southern Texas and Florida.


22.   Digitaria didactyla Willd.
Blue Couch

Plants perennial; stoloniferous and rhizomatous, mat-forming. Culms 15-40(63) cm, rooting and branching from the lower nodes. Sheaths densely to sparsely hairy, with 3-5 mm papillose-based hairs; ligules 1-1.5 mm; blades 2.5-7 cm long, 1-3 mm wide, flat or folded, usually glabrous, green to bluish-green. Panicles with 2-4 spikelike primary branches digitately arranged; primary branches 2-7 cm, axes wing-margined, wings at least 1/2 as wide as the midribs, spikelets somewhat imbricate, in unequally pedicellate pairs; secondary branches rarely present; pedicels not adnate to the branches; shorter pedicels 1-1.5 mm; longer pedicels 2-3 mm; axillary panicles not present. Spikelets homomorphic, 2-2.8 mm long, about 0.8 mm wide. Lower glumes to 0.3 mm, triangular; upper glumes from 1/2-3/4 as long as the spikelets, 3-veined, pilose on the margins and sometimes between the veins; upper lemmas equaling the spikelets, prominently 7-veined, veins equally spaced, margins and sometimes the intercostal regions pilose, hairs 0.3-0.5 mm; upper lemmas slightly shorter than the lower lemmas, almost smooth, gray, sometimes purple-tinged, at maturity. 2n = unknown.

A native of Africa, Digitaria didactyla is often cultivated as a lawn grass in tropical and subtropical regions. It has been grown experimentally in Florida, but is not otherwise known from the Flora region.


23.   Digitaria eriantha Steud.

Plants perennial; sometimes stoloniferous, stolons to 6 m, or cespitose, with or without rhizomes, rhizomes, if present, short, giving the plants knotty bases. Culms 35-140 cm, erect or decumbent, not rooting at the basal nodes. Basal sheaths glabrous or pubescent, often densely so, with 4-6 mm papillose-based hairs; ligules (1.8)3-5 mm, erose and ciliate; blades 5-40 cm long, 3-6 mm wide, scabridulous, often also papillose-hairy. Panicles with 3-15 spikelike primary branches, digitate or with rachises to 3 cm; primary branches 5-25 cm, wing-margined, wings wider than the midribs, with spikelets in unequally pedicellate pairs; shorter pedicels 0.5-1.5 mm; longer pedicels 1.5-3 mm. Spikelets homomorphic, 2.8-3.5 mm, narrowly lanceolate to narrowly elliptic. Lower glumes 0.3-0.5 mm, veinless, acute; upper glumes 1.7-1.9 mm, wooly pubescent; lower lemmas 2.5-3.5 mm, 7-veined, veins unequally spaced and smooth, occasionally the lateral veins scabridulous over the distal 1/4, margins and region between the 2 inner lateral veins appressed-pubescent, with 0.5-1.5 mm hairs; upper lemmas gray when immature, becoming brownish at maturity; anthers 1.2-1.6 mm, purple. 2n = 36.

Digitaria eriantha is an African species that is widely cultivated in warm climates as a pasture grass. Several cultivars have been released for forage and hay use. The appearance of the spikelets varies considerably with the length of the hairs, those of subsp. eriantha usually being longer than those of subsp. pentzii

The cultivar Digitaria umfolozi D.W. Hall ('Survenola'), a hybrid between D. setivalva [= D. eriantha subsp. eriantha] and D. decumbens [= D. eriantha subsp. pentzii] has been released for use in the tropics and on well-fertilized upland soils in Florida. It is described as having much wider leaf blades than any other cultivars that have been released so far (usually 10-13 mm wide, rather than usually less than 8 mm) and glabrous leaf sheaths.

1
Plants cespitose ..... subsp. eriantha
Plants stoloniferous ..... subsp. pentzii


Digitaria eriantha Steud. subsp. eriantha

Plants cespitose, rhizomatous, rhizomes short. Basal sheaths hirsute.

Digitaria eriantha subsp. eriantha is seed-producing, but it is not clear whether it is being grown in the Flora region.


Digitaria eriantha subsp. pentzii (Stent) Kok

Plants stoloniferous (the stolons to 6 m), sterile. Basal sheaths glabrous or hirsute. 2n = 27 (for Digitaria decumbens).

In the Western Hemisphere, D. eriantha subsp. pentzii has traditionally been referred to as D. decumbens Stent. It is widely cultivated as a forage grass throughout the tropics at low and intermediate altitudes (up to 2000 m). It does not set seed; propagation is by sprigging the stolons.


24.   Digitaria milanjiana (Rendle) Stapf

Plants perennial; rhizomatous and stoloniferous. Culms 50-250 cm, erect or decumbent, rooting or not at the lower nodes. Basal sheaths glabrous or variously pubescent (pilose, rarely tomentose or with papillose-based hairs); upper sheaths glabrous; ligules 0.8-2.5 mm; blades 6-15(30) cm long, 3.5-8.5(13) mm wide, glabrous adaxially, rarely hirsute, with papillose-based hairs basally, margins scabridulous. Panicles with 2-18 spikelike primary branches, these digitate or with rachises to 6 cm; primary branches 5-25 cm, axes wing-margined, wings about as wide as the midribs, with spikelets in unequally pedicellate pairs; secondary branches rarely present; shorter pedicels 0.2-0.3 mm; longer pedicels 1-1.5 mm. Spikelets homomorphic, 2.5-3.5 mm long, 0.7-0.9 mm wide, lanceolate. Lower glumes 0.2-0.5 mm, acute to truncate; upper glumes (1.2)1.6-2.3 mm, from 1/5 as long as to almost equaling the spikelets; lower lemmas 2.5-3.5 mm, 7-veined, veins unequally spaced, midvein and lateral veins scabrous at least on the distal 1/2, margins and region between the inner 2 lateral veins with straight, yellowish, 0.6-1 mm hairs; upper lemmas gray to tan at maturity. 2n = 18, 34, 36, 45, 54, 72(?).

Digitaria milanjiana is native to tropical and subtropical Africa. It has been found as an escape from experimental plantings in Florida.


25.   Digitaria velutina (Forssk.) P. Beauv.

Plants of indefinite duration; loosely cespitose to straggling. Culms 15-80 m, decumbent, rooting and branching at the lower nodes. Sheaths pilose, with papillose-based hairs; ligules 1.8-2 mm; blades 4-15 cm long, 3-10 mm wide, pilose, with papillose-based hairs. Panicles with 5-18 spikelike primary branches on 2.5-5 cm rachises, lower branches usually verticillate; primary branches 3.5-10 cm long, 0.3-0.5 mm wide, narrowly wing-margined, wings less than 1/2 as wide as the midribs, with spikelets in unequally pedicellate pairs; secondary branches often present, often highly divergent; shorter pedicels 0.2-0.5 mm; longer pedicels 0.8-1.1 mm. Spikelets 1.5-2 mm long, about 0.5 mm wide, elliptic-lanceolate. Lower glumes absent or to 0.2 mm; upper glumes 1.5-1.7 mm, usually to 3/4 as long as the spikelets, 3-veined, villous between the veins, hairs tapering or parallel-sided; lower lemmas about as long as the spikelets, 7-veined, veins unequally spaced, 2 veins crowded together near each margin, 3 inner veins well-separated, pubescent on the margins and between the inner lateral veins, hairs about 0.2 mm, sometimes sparse, lateral veins smooth throughout or scabridulous only on the distal 1/3; upper lemmas 1.5-1.7 mm, usually gray at maturity, sometimes brown; anthers about 0.5 mm. 2n = 18.

Digitaria velutina is an African species, appearing on the noxious weed list of the U.S. Department of Agriculture. It has been erroneously reported as occurring in Texas (Kartesz and Meacham 1999).


26.   Digitaria horizontalis Willd.

Plants of indefinite duration; sprawling. Culms to 1 m, erect portion 20-25 cm, decumbent, rooting and branching freely at the nodes. Sheaths usually with scattered papillose-based hairs, hairs more abundant on the lower sheaths; ligules 1.5-1.8 mm, erose; blades 3-14 cm long, 3-9 mm wide, evenly, often densely pubescent adaxially, hairs papillose-based. Panicles with 2-14 spikelike branches attached to 4-15 cm rachises, lower branches whorled, upper branches often paired or solitary; lower nodes with hairs more than 0.4 mm; primary branches 4-12 cm, axes 0.4-0.7 mm wide, wing-margined, wings at least 1/2 as wide as the midribs, often with scattered 1-4 mm hairs proximally, with spikelets in unequally pedicellate pairs on the proximal and middle portion of the branches; secondary branches rarely present; shorter pedicels 0.3-0.5 mm; longer pedicels 1.3-2 mm. Spikelets homomorphic, 2.1-2.4 mm, narrowly ovate. Lower glumes 0.1-0.2 mm; upper glumes 1-1.1 mm, 1/3-1/2 as long as the spikelets, 3-veined, margins and apices ciliate; lower lemmas about as long as the spikelets, lanceolate, 7-veined, lateral 3 veins on each side unequally or equally spaced, smooth or scabrous over the distal 1/3, lemma margins and the region between the second and third veins densely pubescent, hairs 0.05-0.1 mm, white; upper lemmas slightly shorter than the lower lemmas, yellowish or grayish when immature, becoming light brown at maturity, minutely striate. Caryopses about 1.8 mm, tan. 2n = 36.

Digitaria horizontalis is native to tropical regions of the Americas. It has been found in hammocks and disturbed areas in central and southern Florida and at a few other locations in the southeastern United States, including ballast dumps in Mobile, Alabama.


27.   Digitaria nuda Schumach.

Plants annual or of indefinite duration. Culms 20-60 cm, glabrous, decumbent, rooting and branching from the lower nodes, geniculate above. Sheaths glabrous or with long hairs near the base; ligules 0.8-2.5 mm; blades 2-13.5 cm long, 1.5-2.5 mm wide, glabrous on both surfaces or the adaxial surface with a few long hairs near the base. Panicles with 3-8 spikelike primary branches, these digitate or with rachises to 2 cm long; lower panicle nodes with hairs at least 0.4 mm; primary branches 4-15.5(20) cm long, 0.4-0.8 mm wide, axes wing-margined, wings more than 1/2 as wide as the midribs, proximal portions of the branches often with scattered 1-4 mm hairs, with spikelets in unequally pedicellate pairs on the lower and middle portions of the branches; secondary branches absent; pedicels not adnate to the branches. Spikelets homomorphic, 1.7-2.8 mm long, 0.5-0.8 mm wide. Lower glumes absent or to 0.2 mm; upper glumes 1-2.2 mm, 0.4-0.8 times as long as the spikelets; lower lemmas about as long as the spikelets, 7-veined, veins smooth, lateral veins usually equally spaced, sometimes the inner lateral veins more distant from the other 2, intercostal regions adjacent to the midveins glabrous, those between the lateral veins with 0.5-1 mm hairs, hairs initially appressed, sometimes strongly divergent at maturity; upper lemmas yellow to gray when immature, becoming brown at maturity; anthers 0.3-0.6 mm. 2n = unknown.

Digitaria nuda is an African species thatis now established in tropical regions throughout the world, including the Americas. So far as is known, it has only been collected once in the Flora region.


28.   Digitaria sanguinalis (L.) Scop.
Hairy Crabgrass, Digitaire Sanguine

Plants annual. Culms 20-70(112), often decumbent and rooting at the lower nodes. Sheaths keeled, usually sparsely pubescent with papillose-based hairs; ligules 0.5-2.6 mm; blades 2-11(14) cm long, 3-8(12) mm wide, usually with papillose-based hairs on both surfaces, sometimes glabrous. Panicles with 4-13 spikelike primary branches, these subdigitate or on rachises to 6 cm; primary branches 3-30 cm long, 0.7-1.5 mmwide, flattened and winged, wings more than 1/2 as wide as the midribs, lower and middle portion of the branches with spikelets in unequally pedicellate pairs, pedicels not adnate to the branches; secondary branches rarely present. Spikelets homomorphic, 1.7-3.4 mm long, 0.7-1.1 mm wide. Lower glumes 0.2-0.4 mm long, veinless; upper glumes 0.9-2 mm, 1/3-1/2 as long as the spikelets, 3-veined, pubescent on the margins; lower lemmas usually exceeded or equaled by the upper florets, sometimes exceeding them but by no more than 0.2 mm, glabrous, 7-veined, lateral (or all) veins scabrous throughout or smooth on the lower 1/3(1/2) and scabrous distally, 3 middle veins usually widely spaced, remaining veins on each side close together and near the margins; upper lemmas 1.7-3 mm, yellow or gray, frequently purple-tinged when immature, often becoming brown at maturity; anthers 0.5-0.9 mm. 2n = 36, 28, 34, 54.

Digitaria sanguinalis is a weedy Eurasian species that is now found in waste ground of fields, gardens, and lawns throughout much of the world, including the Flora region.


29.   Digitaria bicornis (Lam.) Roem. & Schult.

Plants of indefinite duration; sometimes stoloniferous. Culms with erect portion 10-85 cm, long-decumbent, rooting and branching at the lower nodes. Sheaths with papillose-based hairs or the upper sheaths glabrous; ligules 1-4 mm; blades 3-14 cm long, 2-9 mm wide, mostly glabrous but the adaxial surfaces with papillose-based hairs basally. Panicles with (2)3-6 spikelike primary branches, these digitate or a few solitary branches below; lowest nodes glabrous or with hairs less than 0.4 mm; primary branches 6.5-21 cm long, 0.6-1.3 mm wide, axes winged, wings at least 1/2 as wide as the midribs, lower and middle portions with spikelets in unequally pedicellate pairs, pedicels not adnate to the branches; secondary branches absent; shorter pedicels about 0.2 mm; longer pedicels to 2 mm. Spikelets 2.6-3.7 mm, spikelet pairs dimorphic in their pubescence and venation pattern of the lower lemmas. Lower glumes absent or to 0.9 mm, deltoid or bifid; upper glumes 1.7-2.8 mm, 1/2-3/4 as long as the spikelets, 3-veined; lower lemmas 7-veined, veins smooth; lower lemmas of shortly pedicellate spikelets with 3 equally spaced, glabrous or shortly pubescent central veins, lemma margins and the region between the 2 lateral veins with appressed or spreading, 0.5-1 mm hairs; lower lemmas of long-pedicellate spikelets with unequally spaced veins, midvein well-separatedfrom the 3 lateral veins, lateral veins crowded together near the margins, lemma margins and the region between the 2 inner lateral veins hairy with appressed or strongly divergent, 1-2 mm hairs, sometimes also with longer, glassy yellow hairs; upper lemmas of all spikelets usually yellow or gray, sometimes light brown, at maturity; anthers 0.5-0.6 mm. 2n = 54, 72.

Digitaria bicornis is a common species on the sandy coastal plain of the southeastern United States. Its range extends through Mexico to Costa Rica and northern South America, as well as to the West Indies. The Californian record reflects a 1926 collection; the species is not known to be established in the state.


30.   Digitaria ciliaris (Retz.) Koeler
Southern Crabgrass

Plants annual or of indefinite duration. Culms 10-100 cm long, erect portion 30-60 cm, long-decumbent, rooting and branching at the decumbent nodes, sparingly branched or unbranched from the upper nodes; nodes 2-5, glabrous. Sheaths with papillose-based hairs; ligules 2-3.5 mm, erose; blades 1.5-14.4(18.9) cm long, 3-9 mm wide, flat, glabrous, a few scattered papillose-based hairs at the base of the adaxial surfaces (occasionally overthe whole adaxial surface), usually also scabrous on both surfaces. Panicles with 2-10 spikelike primary branches, these digitate or in 1-3 whorls on rachises to 2 cm; lowest panicle nodes with hairs more than 0.4 mm; primary branches 3-24 cm long, 0.6-1.2(2) mm wide, glabrous or with less than 1 mm hairs, axes wing-margined, wings at least 1/2 as wide as the midribs, lower and middle portions of the branches with spikelets in unequally pedicellate pairs; secondary branches absent; shorter pedicels 0.5-1 mm; longer pedicels 1.5-4 mm. Spikelets (2.7)2.8-4.1 mm long, homomorphic. Lower glumes 0.2-0.8 mm, acute; upper glumes (1.2)1.5-2.7 mm, about 2/3 to almost as long as the spikelet, 3-veined, margins and apices pilose; lower lemmas 2.7-4.1 mm, 7-veined, veins unequally spaced, outer 3 veins crowded together near each margin, well-separated from the midvein, usually smooth, occasionally the lateral veins scabridulous on the distal 1/3, margins and regions between the 2 inner lateral veins hairy, hairs 0.5-1 mm (rarely glabrous), sometimes also with glassy yellow hairs between the 2 inner lateral veins, these more common on the upper spikelets; upper lemmas 2.5-4 mm, glabrous, yellow, tan, or gray when immature, becoming brown, often purple-tinged (occasionally completely purple) at maturity; anthers 0.6-1 mm. 2n = 36 [J.H. Hunziker, F.O. Zuloaga, O. Morrone, and A. Escobar. 1998. Estudios cromosómicos en Paniceae sudamericanas (Poaceae: Panicoideae). Darwiniana 35:29-36], 54.

Digitaria ciliaris is a weedy species, found in open, disturbed areas in most warm-temperate to tropical regions, primarily in the eastern United States. It is particularly abundant in the southeast. So far as is known, the two varieties distinguished in the following key do not differ in any other characters. They are recognized here pending further study.

1
Lower lemmas without glassy yellow hairs ..... var. ciliaris
Lower lemmas with glassy yellow hairs ..... var. chrysoblephara

Digitaria ciliaris var. ciliaris is the more common of the two varieties in the Flora region. Digitaria ciliaris var. chrysoblephara (Fig. & De Not.) R.R. Stewart is more common in southeast Asia, but it has been found in the northeastern United States.


31.   Digitaria setigera Roth

Plants of indefinite duration. Culms to 120 cm tall, bases long-decumbent and rooting at the lower nodes. Sheaths with papillose-based hairs; ligules 2.5-3.5 mm; blades 4-28 cm long, 4-12 mm wide, scabrous, usually with some scattered papillose-based hairs on the base of the adaxial surfaces, sometimes with hairs all over. Panicles with 3-11 spikelike primary branches in 1-several whorls, rachises to 6 cm; primary branches 5-15 cm, axes wing-margined, wings more than 1/2 as wide as the midribs, lower and middle portions with spikelets in unequally pedicellate pairs; secondary branches absent; shorter pedicels 0.3-0.8 mm; longer pedicels 1.7-2.7 mm. Spikelets 2.4-3.5 mm, homomorphic, ovate. Lower glumes absent or to 0.1 mm; upper glumes 0.2-1.3 mm, 1/6-1/3 as long as the spikelets, 1-3-veined, margins and apices with appressed, white hairs about 0.5 mm, truncate or bilobed; lower lemmas (5)7-veined, veins smooth or scabrous only over the distal 1/3, unequally spaced, margins and lateral intercostal regions silky-ciliate; upper lemmas tan or gray when immature, brown at maturity, acuminate; anthers 0.6-1.3 mm. 2n = 70, 72.

Digitaria setigera is native to southeastern Asia. It is now established in tropical America, growing in disturbed habitats in Florida and Central America, and probably in tropical South America. It has often been confused with D. sanguinalis.

Plants in the Flora region belong to Digitaria setigera Roth var. setigera. Unlike plants of D. setigera var. calliblepharata (Henrard) Veldkamp, they do not have large, glassy hairs on their lower lemmas.