25.20   SETARIA P. Beauv.
James M. Rominger

Plants annual or perennial; cespitose, rarely rhizomatous. Culms 10-600 cm, erect or decumbent. Ligules membranous and ciliate or of hairs; blades flat, folded, or involute, or plicate and petiolate (subg. Ptychophyllum). Inflorescences terminal, panicles, usually dense and spikelike, occasionally loose and open; disarticulation usually below the glumes, spikelets falling intact, bristles persistent. Spikelets 1-5 mm, usually lanceoloid-ellipsoid, rarely globose, turgid, subsessile to short pedicellate, in fascicles on short branches or single on a short branch, some or all subtended by 1-several, terete bristles (sterile branchlets). Lower glumes membranous, not saccate, less than 1/2 as long as the spikelets, 1-7-veined; upper glumes membranous to herbaceous at maturity, 1/2 as long as to nearly equaling the upper lemmas, 3-9-veined; lower florets staminate or sterile; lower lemmas membranous, equaling or rarely exceeding the upper lemmas, rarely absent, not constricted or indurate basally, 5-7-veined; lower paleas usually hyaline to membranous at maturity, rarely absent or reduced, veins not keeled; upper florets bisexual; upper lemmas and paleas indurate, transversely rugose, rarely smooth; anthers 3, not penicillate; styles 2, free or fused basally, white or red. Caryopses small, ellipsoid to subglobose, compressed dorsiventrally. x = 9. Name from the Latin seta, bristle and aria, possessing.

Setaria, a genus of about 140 species, grows predominantly in tropical and warm-temperate regions, but it is particularly well-represented in Africa, Asia, and South America. Species from the Flora region fall into one of three categories: native to North America, native to South America, or native to the Eastern Hemisphere. There are 27 species in the Flora region; fifteen are native, nine are established introductions, one is cultivated, and two are not established or have been collected only at scattered locations. Several species of the native Setaria macrostachya complex (S. macrostachya, S. leucopila, S. texana, S. villosissima, and S. scheelei) provide valuable forage in the southwestern United States. Setaria italica has been cultivated for centuries in Asia and Europe, providing food for humans and their livestock. The majority of species in temperate North America are aggressive, exotic annuals which collectively are a major nuisance, particularly in the corn and bean fields of the midwestern states.


SELECTED REFERENCES Clayton, W.D.1979. Notes on Setaria (Gramineae). Kew Bull. 33:501-509; Emery, W.H.P. 1957. A cyto-taxonomic study of Setaria macrostachya (Gramineae) and its relatives in the southwestern United States and Mexico. Bull. Torrey Bot. Club 84:94-105; Fox, W.E., III and S.L. Hatch. 1999. New combinations in Setaria (Poaceae: Paniceae). Sida 18:1037-1047; 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.; Hubbard, F.T.1915. A taxonomic study of Setaria italica and its immediate allies. Amer. J. Bot. 2:169-198; Reeder, J.R. 1994. Setaria villosissima (Gramineae) in Arizona: Fact or fiction. Phytologia 77:452-455; Rominger, J.M.1962. Taxonomy of Setaria (Gramineae) in North America. Illinois Biol. Monogr. 29:1-132.

1
Terminal spikelet of each panicle branch subtended by a single bristle, single bristles occasionally also present below the other spikelets (2)
All spikelets subtended by 1-several bristles (subg. Setaria) (6)
2
Blades not plicate, less than 10 mm wide; bristles present only below the terminal spikelets (3)
Blades plicate, more than 10 mm wide; a single bristle sometimes present below the non-terminal spikelets (subg. Ptychophyllum) (4)
3
Panicles nodding; spikelets 2-ranked on the branch axes (subg. Paurochaetium) ..... 4. S. chapmanii
Panicles erect; spikelets randomly distributed on the branch axes (subg. Reverchoniae) ..... 5. S. reverchonii
4
Plants annual; blades 10-25 mm wide; rachises villous ..... 1. S. barbata
Plants perennial; blades 20-80 mm wide; rachises scabrous or puberulent (5)
5
Panicles loosely open, branches lax, 6-10 cm long ..... 2. S. palmifolia
Panicles lanceoloid, branches stiff, 2-5 cm long ..... 3. S. megaphylla
6
Bristles 4-12 below each spikelet (7)
Bristles 1-3 (rarely 6) below each spikelet (10)
7
Plants annual (8)
Plants perennial (9)
8
Panicles erect; bristles 3-8 mm long; spikelets 2-3.4 mm long; blades 4-10 mm wide ..... 27. S. pumila
Panicles arching and drooping from near the base; bristles about 10 mm long; spikelets 2.5-3 mm long; blades 10-20 mm wide ..... 24. S. faberi
9
Panicles 3-8(10) cm long, yellow to purple; knotty rhizomes present; native ..... 25. S. parviflora
Panicles 5-25 cm long, usually orange to purple; stout rhizomes present; introduced ..... 26. S. sphacelata
10
Bristles retrorsely scabrous (11)
Bristles antrorsely scabrous (12)
11
Margins of sheaths glabrous; blades strigose on the abaxial surfaces; subtropical ..... 19. S. adhaerans
Margins of sheaths ciliate distally; blades scabrous on the abaxial surfaces; temperate ..... 20. S. verticillata
12
Plants perennial (13)
Plants annual (20)
13
Spikelets 2.8-3.2 mm long (14)
Spikelets 1.9-2.8(3) mm long (15)
14
Blades scabrous; plants of Florida and Georgia ..... 11. S. macrosperma
Blades pubescent; plants of Texas and possibly Arizona ...... 10. S. villosissima
15
Panicles 2-6cm long; spikelets 1.9-2.1 mm long; culms branching at the upper nodes ...... 6. S. texana
Panicles 5-30 cm long; spikelets 2-2.8(3) mm long; culms seldom branching at the upper nodes (16)
16
Lower paleas narrow, 1/2-3/4 as long as the lemmas; spikelets elliptical (17)
Lower paleas broad, subequal to the lemmas in length; spikelets subspherical to ovate-lanceolate (18)
17
Blades usually less than 5 mm wide; panicles 6-15 cm, columnar; bristles ascending ..... 8. S. leucopila
Blades usually more than 5 mm wide; panicles 15-25 cm, tapering to the apex; bristles diverging ..... 9. S. scheelei
18
Panicles dense, cylindrical; spikelets subspherical ..... 7. S. macrostachya
Panicles interrupted, attenuate; spikelets ovate-lanceolate (19)
19
Blades 6-12 mm wide; lower glumes 1/2 as long as the spikelets ..... 12. S. setosa
Blades mostly less than 5 mm wide; lower glumes about 1/3 as long as the spikelets ..... 13. S. rariflora
20
Upper glumes and lower lemmas with 7 veins, the outer pair of veins not coalescing with the inner 5; lower paleas absent ..... 15. S. liebmannii
Upper glumes and lower lemmas with 5-7 veins, all of which coalesce near the apices; lower paleas present, sometimes reduced (21)
21
Upper lemmas smooth and shiny, occasionally obscurely transversely rugose (22)
Upper lemmas distinctly transversely rugose, dull (23)
22
Spikelets about 2 mm long, lower paleas equal to the lower lemmas ..... 18. S. magna
Spikelets about 3 mm long, lower paleas absent or up to 1/2 as long as the lower lemmas ..... 23. S. italica
23
Upper lemmas coarsely rugose (24)
Upper lemmas finely rugose (25)
24
Panicles densely spicate; rachises sparsely villous; plants of the southeastern United States ..... 17. S. corrugata
Panicles loosely spicate; rachises scabrous; plants of southern Arizona ..... 16. S. arizonica
25
Panicles verticillate or loosely spicate; rachises visible, scabrous or hispid (26)
Panicles densely spicate; rachises not visible, villous (27)
26
Panicles verticillate; rachises scabrous; cauline nodes glabrous ..... 21. S. verticilliformis
Panicles loosely spicate, interrupted; rachises hispid; cauline nodes pubescent ..... 14. S. grisebachii
27
Blades softly pilose on the upper surface; spikelets 2.5-3 mm long; panicles nodding from the base .....24. S. faberi
Blades scabrous; spikelets 1.8-2.2 mm long; panicles nodding only from near the apex ..... 22. S. viridis


Setaria subg. Ptychophyllum (A. Braun) Hitchc.

Plants usually robust perennials. Blades broad, plicate. Panicles usually loose; bristles solitary, subtending the terminal spikelet of each ultimate branchlet, occasionally present beneath the other spikelets. Spikelets 2.5-5 mm, slender, often acuminate.

Setaria subg. Ptychophyllum is primarily an American taxon, but is also found in the Eastern Hemisphere. Three species, all introduced, have been found in the Flora region.


1.   Setaria barbata (Lam.) Kunth
Mary Grass, Corn Grass

Plants annual. Culms 50-200 cm; nodes pubescent. Sheaths with ciliate margins distally; ligules about 1 mm, ciliate; blades 10-25 mm wide, plicate, both surfaces scabrous, adaxial surfaces with parallel rows of papillose-based hairs. Panicles to 20 cm, open; branches 2-4 cm, axes villous; bristles solitary, usually only present below the terminal spikelet on each branch, occasionally below non-terminal spikelets, 5-8 mm, flexible. Spikelets 2.5-3 mm. Lower glumes about 1 mm, orbicular, 3-5-veined; upper glumes about 2 mm, ovate, 7-veined; lower lemmas about 2.5 mm, slightly coriaceous, acute; lower paleas about equaling the lower lemmas in length and width; upper lemmas about 2.3 mm, strongly transversely rugose; upper paleas enclosed. 2n = 54, 56.

Setaria barbata is an African species that was apparently introduced to the Western Hemisphere from Asia. It is now common throughout the West Indies, but rare in the Flora region.


2.   Setaria palmifolia (J. König) Stapf
Palmgrass

Plants perennial. Culms 1-2 m. Sheaths strigose, margins with stiff hairs; collars hispid; ligules about 2 mm, of hairs; blades to 50 cm long, 20-80 mm wide, plicate, tapering at both ends, abaxial surfaces sparsely strigose, adaxial surfaces short pubescent near the base. Panicles to 40 cm, open; branches 6-10 cm, loosely flexible, axes scabrous; bristles solitary, usually present only below the terminal spikelet on each branch, occasionally below non-terminal spikelets, about 5 mm. Spikelets 3-4 mm, elliptic, acuminate. Lower glumes 1/2 as long as the spikelets, obtuse, 3-4-veined; upper glumes nearly equaling the upper lemmas, 7-veined, acute; lower lemmas exceeding the upper lemmas, 5-veined, apices involute; lower paleas nearly equaling the lower lemmas in length and width; upper lemmas obscurely transversely rugose, yellow, apiculate. 2n = 54.

Setaria palmifolia is primarily an Asiatic species. It is a common species in Jamaica, and has been reported from scattered locations around the southern coast of the United States. In the Flora region it is occasionally cultivated as an ornamental for the conspicuous, plicate leaves and large panicles. In Southeast Asia the grains are eaten as a substitute for rice and the tender, thickened shoots as a vegetable.


3.   Setaria megaphylla (Steud.) T. Durand & Schinz
Bigleaf Bristlegrass

Plants perennial. Culms 100-200 cm, nodes villous. Sheaths sparsely strigose or glabrous; ligules about 2 mm, of hairs; blades 40-60 cm long, 20-80 mm wide, strongly plicate, with scattered hairs on each surface. Panicles 30-60 cm, lanceoloid; branches 2-5 cm, stiff; bristles solitary, usually present only below the terminal spikelet on each branch, occasionally below non-terminal spikelets, 1-1.5 cm. Spikelets 3-3.5 mm. Lower glumes1/2 as long as the spikelets, 3-veined; upper glumes 2/3 as long as the spikelets, 5-7-veined; lower lemmas equaling the upper lemmas, 5-veined; lower paleas absent or reduced to a small scale; upper lemmas about 3 mm, nearly smooth, shiny. 2n = 54.

Setaria megaphylla is a species of tropical Africa and tropical America that has become established in Florida. Hitchcock (1951) stated that S. poiretiana (Schult.) Kunth was occasionally cultivated in the United States, but he was referring to S. megaphylla.


Setaria subg. Paurochaetium (Hitchc. & Chase) Rominger

Plants perennial. Culms tufted, erect. Blades 1-7 mm wide, not plicate. Panicles narrow, usually nodding, more or less interrupted; rachises scabridulous or scabrous, sometimes also sparsely strigose; branches short, appressed; ultimate branchlets with 1-several spikelets in 2 ranks, terminal spikelets subtended by a 1-6 mm bristle. Spikelets 1.5-2.5 mm, glabrous; lower florets usually paleate; upper lemmas and paleas finely and transversely rugose.

Setaria subg. Paurochaetium, as treated by Fox and Hatch (1999), includes seven taxa and extends from southern Florida through the West Indies into the Yucatan region of Mexico and Belize. One species, S. chapmanii, grows in the Flora region.

Setaria subg. Paurochaetium usually differs from subg. Reverchoniae in its 2-ranked and smaller spikelets and in the absence of a palea in the lower floret. Unfortunately, S. chapmanii, the only representative of subg. Paurochaetium in the Flora region, is exceptional within the subgenus in lacking a lower palea.


4.   Setaria chapmanii (Vasey) Pilg.
Chapman's Bristlegrass

Plants perennial; cespitose. Culms 40-100 cm, erect, slender; nodes glabrous. Sheaths mostly glabrous, margins ciliate distally; ligules 0.1-0.4 mm, of stiff hairs; blades 15-40 cm long, 2-5 mm wide,those of the basal leaves involute, those of the cauline leaves flat, adaxial surfaces sparsely pilose basally. Panicles to 35 cm, nodding, slender, interrupted; rachises scabridulous; branches 5-20, erect, axes 0.4-3.2 cm, undulating, with 3-12 spikelets in 2 ranks, a single bristle present below the terminal spikelets; bristles 3-6 mm. Spikelets 1.8-2.2 mm, obovate, turgid. Lower glumes 0.6-0.8 mm, about 1/3 as long as the spikelets, 3-veined; upper glumes equaling the upper lemmas, 5-7-veined; lower lemmas equaling the upper lemmas; lower paleas absent; upper lemmas finely and transversely rugose; anthers 0.9-1.1 mm. 2n = unknown.

Setaria chapmanii is native to soils of coral or shell origin in the Florida Keys, the Bahamas, Cuba, and the Yucatan Peninsula, Mexico. The absence of the lower palea makes S. chapmanii unusual in subg. Paurochaetium.


Setaria subg. Reverchoniae W.E. Fox

Plants perennial. Culms tufted, erect. Blades to 7 mm wide, not plicate. Panicles narrow, erect, more or less interrupted; rachises scabrous; branches short and appressed; ultimate branchlets with 1-several, randomly disposed spikelets, terminal spikelets subtended by a single bristle; bristles 1-6 mm, glabrous. Spikelets 2.1-4.5 mm; lower florets usually without paleas; upper lemmas and paleas finely and transversely rugose.

Setaria subg. Reverchoniae is a monotypic subgenus with a range that extends from western New Mexico and southern Oklahoma through western Texas to northeastern Mexico. It usually differs from subg. Paurochaetium in the random disposition and larger size of the spikelets and, usually, in the absence of the lower palea.


5.   Setaria reverchonii (Vasey) Pilg.

Plants perennial; rhizomatous, rhizomes, short, sometimes knotty. Culms 30-90 cm; nodes glabrous, strigose, or with appressed hairs. Sheaths with papillose-based hairs, sometimes nearly glabrous, margins ciliate distally; ligules 1-2 mm, of stiff hairs; blades 4-30 cm long, 1-7 mm wide, involute, stiff, scabridulous and narrowed basally. Panicles 5-20 cm, erect, slender, interrupted; rachises scabrous; bristles 2-8 mm. Spikelets 2.1-4.5 mm, elliptic to obovate, randomly distributed on the branch axes. Lower glumes 1/2 as long as the spikelets, 5-7-veined; upper glumes equaling the upper lemmas, 7-9-veined; lower lemmas equaling the upper lemmas; lower paleas absent; upper lemmas indurate, finely and transversely rugose; upper paleas similar to the upper lemmas.

Setaria reverchonii grows in sandy prairies and limestone hills from eastern New Mexico, southwestern Oklahoma, and Texas to northern Mexico.

1
Blades usually more than 15 cm long; spikelets 3.5-4.5 mm long ..... subsp. reverchonii
Blades usually less than 15 cm long; spikelets 2.1-3.2 mm long (2)
2
Blades 2-4 mm wide; spikelets about 2.5 mm long ..... subsp. ramiseta
`Blades 4-7 mm wide; spikelets about 3-3.2 mm long ..... subsp. firmula


Setaria reverchonii subsp. firmula (Hitchc. & Chase) W.E. Fox
Knotgrass

Sheaths with papillose-based hairs, sometimes nearly glabrous; blades 4-10 cm long, 4-7 mm wide. Spikelets 3-3.2 mm long, subtending bristles 3-6.4 mm. Lower glumes 5-7-veined; upper glumes 5-7-veined. 2n = 36.

Setaria reverchonii subsp. firmula is endemic to the sandy prairies of southeastern Texas.


Setaria reverchonii subsp. ramiseta (Scribn.) W.E. Fox
Rio Grande Bristlegrass

Sheaths with papillose-based hairs; blades 5-15 cm long, 2-4 mm wide, adaxial surfaces with papillose-based hairs. Spikelets about 2.5 mm, obovate, turgid, subtending bristles 2-4 mm. Lower glumes 5-veined; upper glumes 7-9-veined. 2n = 36.

Setaria reverchonii subsp. ramiseta grows in the sandy plains and prairies of southeastern New Mexico, southern Texas, and northern Mexico.


Setaria reverchonii (Vasey) Pilg. subsp. reverchonii
Reverchon's Bristlegrass

Sheaths almost glabrous; blades 15-30 cm long, 1-3 mm wide. Spikelets 3.5-4.5 mm, elliptic, subtending bristles 5-8 mm. Lower glumes 5-7-veined; upper glumes 7-veined. 2n = 36, 72.

Setaria reverchonii subsp. reverchonii grows in sandy prairies and limestone hills from southwestern Texas to northern Mexico.


Setaria P. Beauv. subg. Setaria

Plants annual or perennial. Blades seldom wider than 20 mm, flat or loosely twisted. Panicles usually contracted, spikelike; branches short, with 1 or more bristles subtending each spikelet. Spikelets obtuse or acutish. Upper lemmas transversely rugose, rarely smooth.

Setaria subg. Setaria is represented in subtropical and temperate regions throughout the world and is the best represented subgenus in the Flora region.


6.   Setaria texana Emery
Texas Bristlegrass

Plants perennial. Culms 30-70 cm, wiry, much branched distally. Sheaths keeled, margins ciliate distally; collars glabrate; ligules to 1 mm, densely ciliate; blades 5-15 cm long, 2-4 mm wide, flat, scabrous. Panicles 2-6 cm, spikelike, basal portion rarely lobed, tapering distally; rachises scabrous to puberulent; bristles solitary, 3-10 mm. Spikelets 1.9-2.1 mm. Lower glumes about 1/2 as long as the spikelets, 3-veined; upper glumes about 3/4 as long as the spikelets, 5-veined; lower lemmas nearly equaling the upper lemmas, 5-veined; lower paleas rudimentary to 1/2 as long as the upper paleas; upper lemmas finely and transversely rugose; upper paleas narrow. 2n = 36.

Setaria texana grows in shaded habitats on sandy loam soils of the Rio Grande plain of south Texas and northeastern Mexico.


7.   Setaria macrostachya Kunth
Plains Bristlegrass

Plants perennial; densely cespitose. Culms 60-120 cm, rarely branched distally, scabrous below the nodes and panicles. Sheaths keeled, glabrous, usually with a few white hairs at the throat; ligules 2-4 mm, densely ciliate; blades 15-20 cm long, 7-15 mm wide, flat, adaxial surface scabrous. Panicles 10-30 cm long, 1-2 cm wide, uniformly thick from the base to the apex, dense, rarely lobed basally; rachises scabrous and loosely pilose; bristles usually solitary, 10-20 mm, soft, antrorsely scabrous. Spikelets 2-2.3 mm, subspherical. Lower glumes 1/3-1/2 as long as the spikelets, 3-5-veined; upper glumes about 3/4 as long as the spikelets, 5-7-veined; lower lemmas equaling the upper lemmas, 5-veined; lower paleas nearly equaling the upper paleas in length and width; upper lemmas transversely rugose; upper paleas convex, ovate. 2n = 54.

Setaria macrostachya is abundant in the desert grasslands of the southwestern United States, particularly in southern Arizona and Texas. It extends south through the highlands of central Mexico. It also grows in the West Indies, but is not common there. It is a valuable forage grass in the Flora region.


8.   Setaria leucopila (Scribn. & Merr.) K. Schum.
Streambed Bristlegrass

Plants perennial; cespitose. Culms 20-100 cm. Sheaths compressed, glabrous, margins villous distally; ligules 1-2.5 mm, ciliate; blades 8-25 cm long, 2-5 mm wide, flat or folded, scabrous on both surfaces. Panicles 6-15 cm, tightly spikelike, pale green; rachises scabrous or villous; bristles usually solitary, 4-15 mm, ascending. Spikelets 2.2-2.8(3) mm, elliptical. Lower glumes about 1/2 as long as the spikelets, 3-veined; upper glumes from 3/4 as long as to equaling the florets, 5-veined; lower lemmas equaling the upper lemmas, 5-veined; lower paleas 1/2-3/4 as long as the upper paleas, lanceolate; upper lemmas apiculate, finely and transversely rugose; upper paleas similar. 2n = 54, 68, 72.

Setaria leucopila grows in the southwestern United States and northern Mexico. It is the most common of the perennial Plains bristlegrasses.


9.   Setaria scheelei (Steud.) Hitchc.
Southwestern Bristlegrass

Plants perennial; cespitose. Culms 60-120 cm; nodes pilose, with appressed hairs. Sheaths glabrous or hispid; ligules 1-2 mm, hispid; blades 15-30 cm long, 6-15 mm wide, flat or folded, scabrous, often pubescent. Panicles 15-25 cm, open, tapering from the base; rachises pubescent to villous; lower branches to 3 cm; bristles usually solitary, 10-35 mm, divergent. Spikelets 2.2-2.5 mm, elliptical. Lower glumes about 1/2 as long as the spikelets, 3-veined; upper glumes from 3/4 as long as to equaling the upper florets, 5-veined; lower lemmas equaling the upper lemmas, 5-veined; lower paleas about 1/2 as long as the upper paleas, lanceolate; upper lemmas finely cross-wrinkled, shortly apiculate; upper paleas ovate-lanceolate. 2n = 54.

Setaria scheelei grows in alluvial soils of canyons and river bottoms of New Mexico and Texas. Within the Flora region, it is particularly abundant in the limestone canyons of the Edwards Plateau of central Texas. Its range extends into central Mexico.


10.   Setaria villosissima (Scribn. & Merr.) K. Schum.
Hairyleaf Bristlegrass

Plants perennial; cespitose. Culms 40-100 cm. Sheaths villous distally, margins ciliate; ligules about 1 mm, densely ciliate, hairs white; blades 15-30 cm long, 5-8 mm wide, both surfaces villous. Panicles 10-20 cm, loosely spicate; bristles usually solitary, 10-20 mm. Spikelets 2.8-3 mm. Lower glumes about 1/3 as long as the spikelets, broadly ovate, 3-veined; upper glumes nearly equaling the spikelets, 5-7-veined; lower lemmas equaling the upper lemmas, 5-veined; lower paleas about 1/5 as long as the upper paleas, lanceolate; upper lemmas finely and transversely undulate-rugose basally, striate and punctate distally; upper paleas similar, ovate-lanceolate. 2n = 54.

Setaria villosissima is a rare species that grows on granitic soils in southwestern Texas and northern Mexico. Hitchcock's (1951) report of S. villosissima growing in Arizona was based on misidentification of a specimen of S. leucopila (Reeder 1994). The villous sheaths and blades and large spikelets of S. villosissima aid in its identification.


11.   Setaria macrosperma (Scribn. & Merr.) K. Schum.
Coral Bristlegrass

Plants perennial. Culms 1-1.5 m. Sheaths prominently keeled, margins villous; ligules 1-3 mm; blades 1-2 cm wide, flat, scabrous. Panicles to 25 cm, loosely spicate; rachises readily visible, sparsely villous; bristles 1(2), 15-30 mm, flexible, antrorsely scabrous. Spikelets 3-3.2 mm. Lower glumes about 1/3 as long as the spikelets, 3-veined; upper glumes about 3/4 as long as the spikelets, 5-veined; lower lemmas equaling the upper lemmas; lower paleas about 1/2 as long as the upper paleas, hyaline, narrow; upper lemmas finely and transversely rugose; upper paleas similar to the upper lemmas. 2n = unknown.

Setaria macrosperma grows on shell or coral islands, and occasionally in old fields or hammocks. It is most frequent in Florida, but has been collected in both South Carolina and Georgia. It also grows in the Bahamas and Mexico.


12.   Setaria setosa (Sw.) P. Beauv.
West Indies Bristlegrass

Plants perennial. Culms 50-100 cm; nodes usually glabrous. Sheaths glabrous or finely pubescent, margins ciliate distally; ligules of 1 mm hairs; blades 15-20 cm long, 6-12 mm wide, flat or folded, often finely pubescent on both surfaces. Panicles 15-20 cm, loosely spikelike, interrupted, attenuate; rachises often villous; branches ascending, lower branches about 2.5 cm; bristles usually solitary, less than 10 mm, antrorsely scabrous. Spikelets 2-2.5 mm, ovate-lanceolate. Lower glumes about 1/2 as long as the spikelets, 3-veined; upper glumes about 2/3 as long as the spikelets, 5-7-veined; lower lemmas equaling the upper lemmas; lower paleas as long as the upper paleas, broad; upper lemmas finely and distinctly transversely rugose. 2n = unknown.

Setaria setosa is native to the West Indies and Mexico. It is probably a recent introduction to Florida, but appears to be established there. The specimen from New Jersey was from a ballast dump; the species is not established in that state.


13.   Setaria rariflora J.C. Mikan
Brazilian Bristlegrass

Plants perennial. Culms 30-70 cm, usually erect, branching profusely at the base; nodes glabrous or sparsely hispid. Sheaths keeled, sparsely pubescent, margins ciliate distally; ligules to 1 mm, of hairs; blades 15-30 cm long, usually less than 5 mm wide, densely pubescent on both surfaces. Panicles 5-15 cm, slender, attenuate, interrupted, sparsely flowered; rachises pubescent; branches mostly shorter than 10 mm, villous; bristles usually solitary, 4-7 mm, antrorsely scabrous. Spikelets about 2 mm, ovate-lanceolate. Lower glumes about 1/3 as long as the spikelets, 3-veined; upper glumes about 1/2 as long as the spikelets, 5-7-veined; lower lemmas equaling the upper lemmas; lower paleas equaling the upper paleas, broad; upper lemmas finely and distinctly transversely rugose; upper paleas similar to the upper lemmas. 2n = unknown.

Setaria rariflora has its center of distribution in South America. It is probably only recently adventive in North America, where it is known from Florida and the West Indies.


14.   Setaria grisebachii E. Fourn.
Grisebach's Bristlegrass

Plants annual. Culms 30-100 cm; nodes pubescent, hairs appressed. Sheaths with ciliate margins; ligules ciliate; blades to 12(25) cm long, to 10(20) mm wide, flat, hispid on both surfaces. Panicles 3-18 cm, loosely spicate, interrupted, often purple; rachises hispid; bristles 1-3, 5-15 mm, flexible, antrorsely scabrous. Spikelets 1.5-2.2 mm. Lower glumes about 1/3 as long as the spikelets, distinctly 3-veined, lateral veins coalescing with the central veins below the apices; upper glumes nearly equaling the upper lemmas, obtuse, 5-veined; lower lemmas equaling the upper lemmas; lower paleas about 1/3 as long as the lower lemmas, narrow; upper lemmas finely and transversely rugose; upper paleas similar to the upper lemmas. 2n = unknown.

Setaria grisebachii is the most widespread and abundant native annual species of Setaria in the southwestern United States. It grows in open ground and extends along the central highlands of Mexico to Guatemala, usually at elevations of 750-2500 m. The specimens from Maryland were collected on chrome ore piles; the species is not established in the state.


15.   Setaria liebmannii E. Fourn.
Liebmann's Bristlegrass

Plants annual. Culms 30-90 cm. Sheaths glabrous, margins ciliate; ligules ciliate; blades to 20 cm long, 10-20 mm wide, flat, scabrous on both surfaces. Panicles 10-25 cm, loosely spicate; rachises scabrous; bristles solitary, 7-15 mm, slender, antrorsely scabrous. Spikelets 2-2.7(3) mm. Lower glumes about 1/3 as long as the spikelets, 3-veined; upper glumes and lower lemmas 7-veined, the 5 central veins coalescing at the apices; lower paleas absent; upper lemmas gibbous, strongly and coarsely transversely rugose; upper paleas similar to the upper lemmas. 2n = 18.

Within the Flora region, Setaria liebmannii is known only from southern Arizona, but it is a common species along the Pacific slope from northern Mexico to Nicaragua, usually growing at elevations below 750 m. The five apically coalescing veins and the additional free pair at the periphery are unique among the Setaria species in the Flora region.


16.   Setaria arizonica Rominger
Arizona Bristlegrass

Plants annual. Culms 25-50 cm; nodes pubescent. Sheaths glabrous, margins ciliate distally; ligules 1-2 mm, ciliate; blades 7-15 cm long, 5-8 mm wide, flat, scabrous, abaxial surface conspicuously hispid over the veins with papillose-based hairs, adaxial surface sparsely hispid over the veins; bristles solitary, 5-15 mm, flexible. Panicles 5-12 cm, loosely spicate; rachises scabrous. Spikelets 1.8-2 mm. Lower glumes about 1/3 as long as the spikelets, 3-veined, lateral veins coalescing with the central vein below the apices; upper glumes about 2/3 as long as the upper lemmas, 5-veined, obtuse; lower paleas equaling the lower lemmas, broad; upper lemmas very strongly and coarsely transversely rugose; upper paleas similar to the upper lemmas. 2n = unknown.

Setaria arizonica is locally abundant in sandy washes on both sides of the Arizona-Sonora border, southwest of Tucson.


17.   Setaria corrugata (Elliott) Schult.
Coastal Bristlegrass

Plants annual. Culms to 100 cm; nodes hispid, hairs appressed. Sheaths glabrous or pilose, margins ciliate distally; ligules about 1 mm, ciliate; blades 15-30 cm long, 4-7 mm wide, flat, scabrous or pubescent. Panicles 3-15 cm, densely spicate; rachises rough hispid and sparsely villous; bristles 1-3, 5-15 mm, flexible, antrorsely scabrous. Spikelets about 2 mm, turgid. Lower glumes 1/3-1/2 as long as the spikelets, 3-5-veined; upper glumes about 3/4 as long as the upper lemmas, 5-7-veined; lower lemmas equaling the upper lemmas; lower paleas 3/4 as long as the lower lemmas, hyaline; upper lemmas very coarsely and transversely rugose; upper paleas similar to the upper lemmas. 2n = unknown.

Setaria corrugata grows in pinelands and cultivated fields along the southeastern coast of the United States. It is also found in Cuba and the Dominican Republic. Superficially, it resembles S. viridis, but is easily distinguished from that species by its coarsely rugose (corrugated) lower lemmas.


18.   Setaria magna Griseb.
Giant Bristlegrass

Plants annual. Culms to 6 m tall, 2-3 cm thick at the base. Sheaths glabrous, smooth or scabrous, margins villous distally; ligules 1-2 mm, ciliate; blades to 60 cm long, to 3.5 cm wide, flat. Panicles to 50 cm long, to 5 cm wide, densely spikelike; rachises densely villous; bristles 1 or 2, 10-20 mm, flexible, antrorsely scabrous. Spikelets about 2 mm, disarticulating between the lower and upper florets. Lower glumes 1/3 as long as the spikelets, 3-veined; upper glumes equaling the lower lemmas, 7-veined; lower florets often staminate; lower lemmas slightly exceeding the upper lemmas; lower paleas equaling the lower lemmas, broad, hyaline, minutely pubescent over the veins; upper lemmas smooth and shiny brown; upper paleas similar to the upper lemmas. 2n = 36.

Setaria magna grows in saline marshes along the eastern coast of the United States. There are also disjunct populations in brackish swamps in Arkansas, and in Texas and southeastern New Mexico as well as in Jamaica, Puerto Rico, Bermuda, Mexico, and Costa Rica. It may have been recently introduced to some of these regions, including inland areas of the Flora region.


19.   Setaria adhaerans (Forssk.) Chiov.
Bur Bristlegrass, Tropical Barbed Bristlegrass

Plants annual. Culms 25-60 cm. Sheaths glabrous throughout; ligules 1-2 mm, of hairs, white; blades usually less than 10 cm long, 5-10 mm wide, flat, broad basally, abaxial surfaces conspicuously strigose with papillose-based hairs, tapering abruptly at the apices; bristles solitary, about 5 mm, retrorsely scabrous. Panicles 2-6 cm, verticillate, green to purple; rachises retrorsely rough hispid. Spikelets 1.5-2.2 mm. Lower glumes about 1/2 as long as the spikelets, obtuse, 1(3)-veined; upper glumes nearly as long as the spikelets, 5-7-veined; lower lemmas equaling to slightly exceeding the upper lemmas; lower paleas less than 1/2 as long as the spikelets, scalelike; upper lemmas finely and transversely rugose; upper paleas similar to the upper lemmas. 2n = 18.

Setaria adhaerans grows in subtropical regions throughout the world. In North America, it is known from the southern United States, northeastern Mexico, Guatemala, Cuba, and the Bahamas. The Californian record may represent a recent introduction.

Setaria adhaerans resembles the temperate S. verticillata, but differs in having shorter panicles, shorter spikelets, glabrous sheath margins, and papillose-based strigose hairs on the blades.


20.   Setaria verticillata (L.) P. Beauv.
Hooked Bristlegrass, Sétaire Verticillée

Plants annual. Culms 30-100 cm; nodes glabrous. Sheaths glabrous, margins ciliate distally; ligules to 1 mm, densely ciliate; blades 5-15 mm wide, flat, abaxial surfaces scabrous. Panicles 5-15 cm, tapering to the apices; rachises retrorsely rough hispid; bristles solitary, 4-7 mm, retrorsely scabrous. Spikelets 2-2.3 mm. Lower glumes about 1/3 as long as the spikelets, obtuse, 1(3)-veined; upper glumes nearly as long as the spikelets; lower paleas about 1/2 as long as the spikelets, broad; upper lemmas finely and transversely rugose; upper paleas similar to the upper lemmas. 2n = 18, 36, 54, 72, 108.

Setaria verticillata is a European adventive that is now common throughout the cooler regions of the contiguous United States and in southern Canada. It is an aggressive weed in the vineyards of central California. Reports of S. carnei Hitchc. from North America are based on misidentification of this species.

Setaria verticillata resembles S. adhaerans, but differs in having longer panicles and spikelets, sheath margins that are ciliate distally, and blades that are scabrous, not hairy. Setaria verticillata is a more northern species than S. adhaerans, but their ranges overlap in the Flora region.


21.   Setaria verticilliformis Dumort.
Barbed Bristlegrass

Plants annual. Culms 30-100 cm; nodes glabrous. Sheaths mostly glabrous, margins ciliate distally; ligules 1-2 mm, of hairs; blades 5-15 mm wide, flat, abaxial surfaces scabrous, adaxial surfaces sparsely villous. Panicles 5-15 cm, tapering to the apices, branches verticillate; rachises antrorsely rough hispid, without villous hairs; bristles solitary, 4-7 mm, antrorsely or retrorsely scabrous. Spikelets 2-2.3 mm. Lower glumes about 1/3 as long as the spikelets, obtuse, 1(3)-veined; upper glumes nearly as long as the spikelets; lower paleas about 1/2 as long as the spikelets, broad; upper lemmas finely and transversely rugose; upper paleas similar to the upper lemmas. 2n = 36.

Setaria verticilliformis is a European adventive that has been found at scattered, mostly urban, locations in the United States.


22.   Setaria viridis (L.) P. Beauv.
Green Bristlegrass, Sétaire Verte

Plants annual. Culms 20-250 cm; nodes glabrous. Sheaths glabrous, sometimes scabridulous, margins ciliate distally; ligules 1-2 mm, ciliate; blades to 20 cm long, 4-25 mm wide, flat, scabrous or smooth, glabrous. Panicles 3-20 cm, densely spicate, nodding only from near the apices; rachises hispid and villous; bristles 1-3, 5-10 mm, antrorsely scabrous, usually green, rarely purple. Spikelets 1.8-2.2 mm. Lower glumes about 1/3 as long as the spikelets, triangular-ovate, 3-veined; upper glumes nearly equaling the upper lemmas, elliptical, 5-6-veined; lower lemmas slightly exceeding the upper lemmas, 5-veined; lower paleas about 1/3 as long as the lower lemmas, hyaline; upper lemmas very finely and transversely rugose, pale green, 5-6-veined; upper paleas similar to the upper lemmas. 2n = 18.

Setaria viridis resembles S. italica but differs in its shorter spikelets and rugose upper florets, and mode of disarticulation. It is also a more aggressive weed.

1
Culms 100-250 cm tall; blades 10-25 mm wide; panicles 10-20 cm long ..... var. major
Culms 20-100 cm tall; blades 4-12 mm wide; panicles 3-8 cm long ..... var. viridis


Setaria viridis var. major (Gaudin) Peterm.
Giant Green Foxtail

Culms 1-2.5 m; nodes 7-12. Blades 10-25 mm wide. Panicles 10-20 cm, producing around 4,000-6,000 caryopses; lower branches about 3 cm, producing a lobed appearance. Spikelets morphologically indistinguishable from those of var. viridis. 2n = 18.

Setaria viridis var. major is a major adventive weed in corn and bean fields of the midwestern United States, dwarfing var. viridis in stature.


Setaria viridis (L.) P. Beauv. var. viridis
Green Foxtail

Culms 20-100 cm; nodes 6-7. Blades 4-12 mm wide. Panicles usually 3-8 cm, producing around 600-800 caryopses. 2n = 18.

Setaria viridis var. viridis is an aggressive adventive weed throughout temperate North America. It is the most common annual representative of Setaria in the Flora region.


23.   Setaria italica (L.) P. Beauv.
Foxtail Millet, Sétaire Italienne, Sétaire d'Italie, Millet des Oiseaux

Plants annual. Culms 10-100 cm. Sheaths mostly glabrous, margins sparsely ciliate; ligules 1-2 mm; blades to 20 cm long, 1-3 cm wide, flat, scabrous. Panicles 8-30 cm, dense, spikelike, occasionally lobed below; rachises hispid to villous; bristles 1-3, to 12 mm, tawny or purple. Spikelets about 3 mm, disarticulating between the lower and upper florets. Lower glumes 3-veined; upper glumes 5-7-veined; lower paleas absent or 1/2 as long as the lower lemmas; upper lemmas very finely and transversely rugose to smooth and shiny, exposed at maturity. 2n = 18.

Setaria italica was cultivated in China as early as 2700 B.C. and during the Stone Age in Europe. Nowdays it is grown mostly for hay or as a pasture grass, but it has been used as a substitute for rice in northern China. It is sometimes cultivated in North America, but it is better known as a weed in moist ditches, mostly in the northeastern United States. It is closely related to S. viridis, differing in the longer (3 mm) spikelets and smooth, shiny upper florets which readily disarticulate above the lower florets. It exhibits considerable variation in seed and bristle color, bristle length, and panicle shape. Using these characters, Hubbard (1915) recognized several infraspecific taxa; they are not treated here.


24.   Setaria faberi R.A.W. Herrm.
Chinese Foxtail, Sétaire Géante

Plants annual. Culms 50-200 cm. Sheaths glabrous, fringed with white hairs; ligules about 2 mm; blades 15-30 cm long, 10-20 mm wide, usually with soft hairs on the adaxial surface. Panicles 6-20 cm, densely spicate, arching and drooping from near the base; rachises densely villous; bristles (1)3(6), about 10 mm. Spikelets 2.5-3 mm. Lower glumes about 1 mm, acute, 3-veined; upper glumes about 2.2 mm, obtuse, 5-veined; lower lemmas about 2.8 mm, obtuse; lower paleas about 2/3 as long as the lower lemmas; upper lemmas pale, finely and distinctly transversely rugose; upper paleas similar to the upper lemmas. 2n = 36.

Setaria faberi spread rapidly throughout the North American corn belt after being accidentally introduced from China in the 1920s. It has become a major nuisance in corn and bean fields of the midwestern United States.


25.   Setaria parviflora (Poir.) Kerguélen
Knotroot Bristlegrass

Plants perennial; rhizomatous, rhizomes short, knotty. Culms 30-120 cm; nodes glabrous. Sheaths glabrous; ligules shorter than 1 mm, of hairs; blades to 25 cm long, 2-8 mm wide, flat, scabrous above. Panicles 3-8(10) cm, of uniform width throughout their length, densely spikelike; rachises scabro-hispid; bristles 4-12, 2-12 mm, antrorsely barbed, yellow to purple. Spikelets 2-2.8 mm, elliptical and turgid. Lower glumes about 1/3 as long as the spikelets, 3-veined; upper glumes 1/2-2/3 as long as the spikelets, 5-veined; lower florets often staminate; lower lemmas occasionally indurate and faintly transversely rugose; lower paleas equaling the lower lemmas; upper lemmas distinctly transversely rugose, often purple-tipped. 2n = 36, 72.

Setaria parviflora is a common, native species of moist ground. It is most frequent along the Atlantic and Gulf coasts, but it also grows from the Central Valley of California east through the central United States and southward through Mexico to Central America, as well as in the West Indies. The plant from Oregon was found on a ballast dump; the species is not established in that state.

Setaria parviflora is the most morphologically diverse and widely distributed of the indigenous perennial species of Setaria.


26.   Setaria sphacelata (Schumach.) Stapf & C.E. Hubb.
African Bristlegrass

Plants perennial; cespitose, rhizomatous, rhizomes stout. Culms 50-150 cm, flattened; nodes glabrous. Sheaths glabrous; blades 15-50 cm long, 4-10 mm wide, flat, rather lax. Panicles 5-25 cm long, 4-8 mm thick (excluding the bristles), densely spicate; bristles 5 or more, 3-6 mm, usually orange to purple. Spikelets 2.5-3 mm, elliptic-oblong. Lower glumes about 1/3 as long as the spikelets; upper florets staminate; upper glumes 1/2-2/3 as long as the spikelets; lower lemmas equaling the upper lemmas; lower paleas equaling the upper paleas, broad; upper lemmas finely and transversely rugose; upper paleas similar to the upper lemmas. 2n = 36, 54.

Setaria sphacelata is native to tropical Africa, but it has been found at a few scattered locations in the Flora region, generally near a port. Clayton (1979) recognized five varieties of S. sphacelata. Those most likely to be introduced into the United States are S. sphacelata (Schumach.) Stapf & C.E. Hubb. var. sphacelata and S. sphacelata var. aurea (Hochst. ex A. Braun) Clayton, with var. aurea differing from var. sphacelata in having fibrous basal leaf sheaths and upper glumes that are often 3-veined.


27.   Setaria pumila (Poir.) Roem. & Schult.`
Yellow Foxtail, Pigeon Grass

Plants annual. Culms 30-130 cm. Sheaths glabrous; ligules ciliate; blades 4-10 mm wide, loosely twisted, adaxial surfaces with papillose-based hairs basally. Panicles 3-15 cm, uniformly thick, erect, densely spicate; rachises hispid; bristles 4-12, 3-8 mm, antrorsely scabrous. Spikelets 2-3.4 mm, strongly turgid. Lower glumes about 1/3 as long as the spikelets, 3-veined, acute; upper glumes about 1/2 as long as the spikelets, 5-veined, ovate; upper florets often staminate; lower lemmas equaling the upper lemmas; lower paleas equaling the lower lemmas, broad; upper lemmas conspicuously exposed, strongly transversely rugose. 2n = 36, 72.

Reports of Setaria nigrirostris (Nees) T. Durand & Schinz in North America have not been verified. It differs from S. pumila in being a rhizomatous perennial with spikelets 3.5-5 mm long and bristles with thickened tips (those of S. pumila are slender throughout). It is a native of southern Africa.

1
Spikelets 3-3.4 mm long; bristles yellow ..... subsp. pumila
Spikelets 2-2.5 mm long; bristles reddish ..... subsp. pallidefusca


Setaria pumila subsp. pallidefusca (Schumach.) B.K. Simon

Blades dark green. Bristles reddish. Spikelets 2-2.5 mm. 2n = 18, 36, 54, 72.

Setaria pumila subsp. pallidefusca is native to tropical Africa. It is now established as a weed in southeastern Louisiana, but it has also been collected in the past on ballast dumps in Portland, Oregon.


Setaria pumila (Poir.) Roem. & Schult. subsp. pumila
Sétaire Glauque

Blades yellowish-green. Bristles yellowish. Spikelets 3-3.4 mm. 2n = 36, 72.

Setaria pumila subsp. pumila is a European adventive that has become a common weed in lawns and cultivated fields throughout temperate North America.