25.15   PENNISETUM Rich.
J.K. Wipff

Plants annual or perennial; habit various. Culms 3-800 cm, not woody, sometimes branching above the base; internodes solid or hollow. Ligules membranous and ciliate, or of hairs, rarely completely membranous; blades sometimes pseudopetiolate. Inflorescences spicate panicles with highly reduced branches termed fascicles; panicles 1-many per plant, terminal on the culms or on both the culms and the secondary branches, or terminal and axillary, or only axillary, usually completely exposed at maturity; rachises usually terete, with (1)5-many fascicles; fascicle axes 0.2-7.5(28) mm, with (1)3-130+ bristles and 1-12 spikelets. Bristles free or fused at the base, disarticulating with the spikelets at maturity; of 3 kinds, outer, inner, and primary, in some species with all 3 kinds present below each spikelet, in others 1 or more kinds missing from some or all of the spikelets; outer (lower) bristles antrorsely scabrous, terete; inner (upper) bristles antrorsely scabrous or long-ciliate, usually flatter and wider than the outer bristles; primary (terminal) bristles located immediately below the spikelets, solitary, antrorsely scabrous or long-ciliate, often longer than the other bristles associated with the spikelet; disarticulation usually at the base of the fascicles, sometimes also beneath the upper florets. Spikelets with 2 florets; lower glumes absent or present, 0-5-veined; upper glumes longer, 0-11-veined; lower florets sterile or staminate; lower lemmas usually as long as the spikelets, membranous, 3-15-veined, margins usually glabrous; lower paleas present or absent; upper lemmas membranous to coriaceous, 5-12-veined; upper paleas shorter than the lemmas but similar in texture; lodicules 0 or 2, glabrous; anthers 3, if present. x = 5, 7, 8, 9 (usually 9). Name from the Latin penna, feather, and seta, bristle, an allusion to the plumose bristles of some species.

Pennisetum has 80-130 species, most of which grow in the tropics and subtropics, and occupy a wide range of habitats. Twenty-five species are native to the Western Hemisphere, but none to the Flora region. Most of the species treated here are cultivated for food, forage, or as ornamental plants. Many species, including several cultivated species, are weedy. Four are classified as noxious weeds by the U.S. Department of Agriculture. Records known to be based on cultivated plants are not included in the distribution maps but, in many cases, it is not possible to determine whether a record is based on a cultivated plant or an escape.

The placement of the boundary between Pennisetum and Cenchrus is contentious. As treated here, Pennisetum has antrorsely scabrous bristles that are not spiny; fascicle axes that terminate in a bristle, and chromosome base numbers of 5, 7, 8, and 9. Cenchrus has retrorsely (rarely antrorsely) scabrous, spiny bristles, fascicle axes that are terminated by a spikelet, and a chromosome base number of 17 (Wipff 2001). In both genera, the bristles are reduced branches (Goebel 1882; Sohns 1955).


SELECTED REFERENCES Brunken, J.N.1977. A systematic study of Pennisetum sect. Pennisetum (Gramineae). Amer. J. Bot. 64:161-176; Brunken, J.N. 1979. Morphometric variation and the classification of Pennisetum section Brevivalvula (Gramineae) in tropical Africa. Bot. J. Linn. Soc. 79:51-64; Chase, A. 1921. The North American species of Pennisetum. Contr. U.S. Natl. Herb. 224:209-234; Goebel, K.I.1882. Beitrage zur Entwickelungsgeschichte einiger Inflorescenzen. Jahrb. Wiss. Bot. 14:1-39; Hignight, K.W., E.C. Basha, and M.A. Hussey. 1991. Cytological and morphological diversity of native apomictic buffelgrass, Pennisetum ciliare (L.) Link. Bot. Gaz. 152:214-218; Schmelzer, G.H. 1997. Review of Pennisetum section Brevivalvula (Poaceae). Euphytica 97:1-20; Sohns, E.R. 1955. Cenchrus and Pennisetum: Fascicle morphology. J. Wash. Acad. Sci. 45:135-143; Wipff, J.K. 1995. A biosystematic study of selected facultative apomictic species of Pennisetum (Poaceae: Paniceae) and their hybrids. Ph.D. dissertation, Texas A&M University, College Station, Texas, U.S.A. 183 pp.; Wipff, J.K. 2001. Nomenclatural changes in Pennisetum (Poaceae: Paniceae). Sida:19:523-530.

NOTE: Pedicel length is the distance from the base of the primary bristles to the base of the terminal spikelets. Fascicle axis lengths and fascicle densities are measured in the middle of the panicle; spikelet measurements refer to the largest spikelets in the fascicles.

1
Plants stoloniferous; panicles axillary, partially or wholly hidden in the leaf sheaths at maturity, the rachises flattened in cross section, with 1-6 fascicles; spikelets 10-22 mm long, bristles mostly shorter than the spikelet ..... 1. P. clandestinum
Plants not stoloniferous; panicles terminal or terminal and axillary, fully exserted at maturity, the rachises terete, with 10-many fascicles; spikelets 2.5-12 mm long, the majority of the bristles as long as or longer than the spikelets (2)
2
Fascicles with only 1 bristle and 1 spikelet ..... 18. P. petiolare
Fascicles with 6 or more bristles and 1-12 spikelets (3)
3
Most or all bristles scabrous, the primary bristles sometimes sparsely and inconspicuously long-ciliate (4)
Bristles, at least the primary bristles, conspicuously long-ciliate (11)
4
Primary bristles not noticeably longer than all the other bristles in the fascicles (5)
Primary bristles noticeably longer than all the other bristles in the fascicles (7)
5
Terminal panicle erect; fascicles with a stipelike base 1.5-5.6 mm long ..... 7. P. alopecuroides
Terminal panicle drooping; fascicles subsessile, the bases 0.4-0.7 mm long (6)
6
Plants green; most of the bristles only slightly longer than the spikelets; upper glumes (7) 9-veined, about as long as the spikelets ..... 4. P. nervosum
Plants purplish; bristles at least twice as long as the spikelets; upper glumes 1-3-veined, usually about 1/2 as long as the spikelets ..... 5. P. macrostachys
7
Panicles dense; rachises with 21-40 fascicles per cm (8)
Panicles less dense; rachises with 5-16 fascicles per cm (9)
8
Rachises pubescent; bristles yellow or purple; leaf blades (4)12-40 mm wide; paleas of lower florets present ..... 2. P. purpureum
Rachises scabrous; bristles white to stramineous; leaf blades 4-12 mm wide; paleas of lower florets absent ..... 6. P. macrourum
9
Panicles drooping, terminal and axillary; leaf blades 19-45 mm wide ..... 8. P. latifolium
Panicles erect, all terminal; leaf blades 2-12 mm wide (10)
10
Plants not rhizomatous; lower part of rachises pubescent ..... 7. P. alopecuroides
Plants rhizomatous; lower part of rachises scabrous ..... 14. P. flaccidum
11
Spikelets 9-12 mm long ..... 11. P. villosum
Spikelets 2.5-7 mm long (12)
12
Fascicles not disarticulating from the rachises; panicles 4-200 cm long; upper lemmas with pubescent margins; caryopses protruding from the florets at maturity ..... 3. P. glaucum
Fascicles disarticulating from the rachises at maturity; panicles 2-37.5 cm long; upper lemmas with glabrous margins; caryopses concealed by the lemmas and paleas at maturity (13)
13
Upper florets readily disarticulating at maturity; upper lemmas smooth and shiny, conspicuously different in texture from the lower lemmas (14)
Upper florets not disarticulating at maturity; lower and upper lemmas similar in texture (15)
14
Fascicles with 6-14 long-ciliate inner bristles and 13-30 scabrous outer bristles; fascicle axes 0.2-0.5 mm long; spikelets sessile ..... 9. P. polystachion
Fascicles with 40-90 long-ciliate inner bristles and 10-20 scabrous outer bristles; fascicle axes 1.5-2.5 mm long; spikelets pedicellate, the pedicels 1-3.5 mm long ..... 10. P. pedicellatum
15
Lower portion of the rachises glabrous, sometimes scabrous (16)
Lower portion of the rachises pubescent (18)
16
Inner bristles neither grooved nor fused, even at the base; spikelets 5.2-6.7 mm long, pedicellate, the pedicels 0.1-0.5 mm long ..... 14. P. flaccidum
Inner bristles grooved and fused, at least at the base; spikelets 2.5-5.6 mm long, sessile (17)
17
Inner bristles fused for up to 1/4 their length; many outer bristles exceeding the spikelets; terminal bristles 10.5-23 mm, noticeably longer than the other bristles in the fascicles ..... 12. P. ciliare
Inner bristles fused for 1/3-1/2 their length; outer bristles not exceeding the spikelets; terminal bristles 2.9-6.5 mm, usually not noticeably longer than other bristles in the fascicles ..... 13. P. setigerum
18
Plants 200-800 cm tall; midculm leaves (4)12-40 mm wide; panicles golden-yellow or dark purple; rachises with 30-40 fascicles per cm ..... 2. P. purpureum
Plants 50-200 cm tall; midculm leaves 2-11 mm wide; panicles white, burgundy, light purple, or pink; rachises with 5-17 fascicles per cm (19)
19
Midculm leaves 2-3.5 mm wide, convolute or folded, green, the midvein noticeably thickened; lower florets of the spikelets usually sterile, sometimes staminate ..... 15. P. setaceum
Midculm leaves 3-11 mm wide, flat, green or burgundy, the midvein not noticeably thickened; lower florets of the spikelets staminate (20)
20
Plants shortly rhizomatous; nodes pubescent; panicles erect to slightly arching, white or purple-tinged; leaves green; ligules 1-1.7 mm long; fascicles with 0-24 terete, scabrous outer bristles ..... 16. P. orientale
Plants not rhizomatous; nodes glabrous; panicles conspicuously drooping, burgundy (rarely whitish-green); leaves burgundy (rarely green); ligules 0.5-0.8 mm long; fascicles with 43-68 terete, scabrous outer bristles ..... 17. P. advena


1.   Pennisetum clandestinum Hochst. ex Chiov.
Kikiyu Grass

Plants perennial; rhizomatous and stoloniferous. Culms 3-45 cm, decumbent, highly branching; nodes glabrous. Sheaths glabrous or pubescent; ligules 1.3-2.2 mm; blades 1-15 cm long, 1-6 mm wide, flat or folded, glabrous or pubescent. Panicles 2-2.7 cm, axillary, concealed in the sheaths; rachises flat, glabrous or scabrous. Fascicles 1-6; axes to 0.5 mm, with 1-2 spikelets; outer and inner bristles alike, 6-15, 0.5-10.9 mm; primary bristles 10-14 mm, usually not noticeably longer than the other bristles. Spikelets 10-22 mm, sessile or pedicellate, pedicels to 0.2 mm; lower glumes usually absent, sometimes to 0.5 mm, veinless; upper glumes 0-1.3(3.5) mm, veinless; lower florets sterile; lower lemmas 10-22 mm, 9-13-veined; lower paleas usually absent; upper lemmas 10-22 mm, 8-12-veined; upper paleas 2-7-veined; anthers 4.7-7 mm, long-exserted from the florets at anthesis. 2n = 36.

Pennisetum clandestinum is native to Africa. It now grows in many parts of the world, often as a forage or lawn grass. The U.S. Department of Agriculture considers it a noxious weed. In parts of the Flora region, it is well-established in lawns.

Scholz (2006; Feddes Repertorium 117: 513) recommended treating P. clandestinum as the only species in a new genus Kikuyuochloa as K. clandestina because of its great morphological different from other members of the tribe. Recent phylogenetic work shows it to be embedded in Pennisetum (Donadío, S., Giussani, L.M., Kellogg, E.A., F.O. Zuloaga & O. Morrone. In press. A molecular phylogeny of Pennisetum and Cenchrus (Poaceae-Paniceae) based on the trnL-F, rpl16 chloroplast markers. Taxon) and, consequently, it is being left in Pennisetum in this treatment. [I thank Drs. E.A. Kellogg and F. Zuolaga for sharing the information about the forthcoming paper with me ahead of publication].

2.   Pennisetum purpureum Schumach.
Elephant Grass

Plants perennial; sometimes rhizomatous. Culms 2-8 m, erect, pubescent beneath the panicle; nodes glabrous or pubescent. Sheaths glabrous or pubescent; ligules 1.5-5 mm; blades 23-125 cm long, (4)12-40 mm wide, flat, glabrous or pubescent. Panicles terminal, 8-30.5 cm long, (10)30-50 mm wide, fully exerted from the leaf sheaths, erect, golden-yellow to dark purple; rachises terete, pubescent. Fascicles 30-40 per cm, disarticulating at maturity; fascicle axes 0.5-1.5 mm, with 1-5 spikelets; outer bristles 20-63, 1.5-10.3 mm, yellow or purple, scabrous; inner bristles 4-6, 9.1-11.5 mm, yellow or purple, sparsely long-ciliate; primary bristles 13-40 mm, noticeably longer than the other bristles, yellow or purple, scabrous. Spikelets 5.9-7 mm, pedicellate; pedicels of terminal spikelets 0.2-0.4 mm, of other spikelets 1.8-3 mm; lower glumes absent or to 0.8 mm; upper glumes 0.8-3 mm, 0-1-veined; lower florets sterile or staminate; lower lemmas 4-5.3 mm, 3-5(6)-veined; lower paleas 4-4.7 mm; anthers absent or 2.2-3.1 mm, penicillate; upper lemmas 4.5-7 mm, subcoriaceous, shiny, 5-7-veined, acuminate; anthers 2.7-3.6 mm, penicillate. Caryopses 1.8-2.2 mm. 2n = 28.

Pennisetum purpureum is native to Africa but now grows in tropical areas throughout the world, frequently becoming naturalized. It is grown as an ornamental in the Flora region, and, less commonly, as forage.


3.   Pennisetum glaucum (L.) R. Br.
Pearl Millet

Plants annual. Culms 50-300 cm, erect, branching; nodes glabrous. Sheaths glabrous or pubescent, with or without ciliate margins; ligules 2-5 mm; blades 15-100 cm long, 7-70 mm wide, flat, glabrous or pubescent. Panicles terminal, 4-200 cm long, 2-70 mm wide, fully exerted from the sheaths, erect; rachises terete, densely pubescent. Fascicles 33-160 per cm; fascicle axes 1-28 mm, persistent, with 1-9 spikelets; outer bristles 44-131, 0.5-6 mm; inner bristles 6-19, 4-6 mm, plumose; primary bristles 5.5-6.3, ciliate, sometimes noticeably longer than the other bristles. Spikelets 3-7 mm; pedicels 0.6-1.8 mm; lower glumes absent or to 1.5 mm, veinless; upper glumes 0.5-3.5 mm, 3-5-veined; lower florets staminate or sterile; lower lemmas 1.5-6 mm, glabrous, 3-7-veined, margins ciliate; lower paleas vestigial or fully developed, margins ciliate; anthers 2.2-2.5 mm, penicillate; upper florets coriaceous, shiny; upper lemmas 4.3-7 mm, 5-7(9)-veined, margins ciliate; upper paleas 3.4-3.9 mm, pubescent, at least near the base, margins ciliate; anthers 2-2.2 mm, penicillate. Caryopses 2-5.5 mm long, 1.6-3.2 mm wide, protruding from the lemma and palea at maturity. 2n = 14.

Pennisetum glaucum, a native of Asia, is cultivated in the United States for grain, forage, and birdseed. It is the most drought tolerant of the tropical cereal crops. Under favorable conditions, 10,000-30,000+ fascicles may be produced. In the Flora region, it is used for soil stabilization, partly because it seldom persists for more than 1-2 years.


4.   Pennisetum nervosum (Nees) Trin.
Bentspike Fountaingrass

Plants perennial; cespitose. Culms 1.5-2(4) m, decumbent, geniculate, branching; nodes glabrous. Leaves green; sheaths glabrous; ligules 0.5-1.5 mm; blades 23-40 cm long, 7-12 mm wide, flat, glabrous. Panicles terminal, 15-22 cm long, 15-21 mm wide, fully exerted from the sheaths, flexible, drooping, green; rachises terete, puberulent. Fascicles 24-49 per cm; fascicle axes 0.4-0.5 mm, with 1 spikelet; most bristles only slightly longer than the spikelets; outer bristles 27-41, 2.4-8.5 mm; inner bristles 3-5, 6.2-11 mm, scabrous; primary bristles 7.6-11.8 mm, not noticeably longer than the other bristles, scabrous. Spikelets 5.2-6.6 mm, sessile; lower glumes 1.7-2.9 mm, 1-veined; upper glumes 4.5-6.3 mm, about as long as the spikelets, (7)9-veined; lower florets sterile; lower lemmas 4.8-6 mm, 7-veined, acuminate to attenuate, midvein excurrent for 0-0.6 mm; lower paleas absent; upper lemmas 4.9-6 mm, 5-veined, acuminate to attenuate, midvein excurrent for 0-0.6 mm; anthers 1.3-1.7 mm. 2n = 36.

Pennisetum nervosum is native to South America. It has been introduced in the Flora region, being known from populations adjacent to the Rio Grande River in Cameron and Hidalgo counties, Texas, and San Diego Couty, California.


5.   Pennisetum macrostachys (Brongn.) Trin.
Pacific Fountaingrass

Plants perennial, or annual in temperate climates; cespitose. Culms 100-300 cm, erect, branching; nodes glabrous. Leaves burgundy; sheaths glabrous; ligules 0.1-0.3 mm; blades 30-53.5 cm long, (15)18-35 mm wide, flat, glabrous. Panicles terminal, (15.5)18-40 cm long, 32-50 mm wide, fully exerted from the sheaths, flexible, drooping, burgundy; rachises terete, shortly pubescent. Fascicles 17-22 per cm; fascicle axes 0.5-0.7 mm, with 1 spikelet; outer bristles 21-40, 1.2-22.3 mm, scabrous; inner bristles absent; primary bristles 20-23 mm, not noticeably longer than the other bristles, scabrous. Spikelets 4.4-4.9 mm, sessile or pedicellate, glabrous; pedicels to 0.1 mm; lower glumes 1.1-1.3 mm, veinless; upper glumes 2.1-2.8 mm, usually about 1/2 as long as the spikelets, 1-3-veined; lower florets staminate (sterile); lower lemmas 4-4.5 mm, 5-veined; lower paleas absent or to 2.6 mm; anthers absent or 1.4-1.6 mm; upper lemmas 4.3-4.8 mm, 5-veined; anthers 1.6-1.8 mm. 2n = 68.

Pennisetum macrostachys is native to the South Pacific. It is grown in the Flora region as an ornamental species, being sold as 'Burgundy Giant'.


6.   Pennisetum macrourum Trin.
Waterside Reed

Plants perennial; rhizomatous. Culms 60-200 cm, erect; nodes pubescent or glabrous. Sheaths pubescent or glabrous; ligules 1-1.7 mm; blades 20-50 cm long, 4-12 mm wide, flat to involute, glabrous, pubescent, or scabrous. Panicles terminal, 6-40 cm long, 20-46 mm wide, fully exerted from the sheaths, erect, white to stramineous; rachises terete, scabrous. Fascicles 21-46 per cm; fascicle axes 0.4-0.6(2) mm, with 1(2) spikelet(s); outer bristles 15-20, 2.5-8 mm; inner bristles 8-10, 4-9 mm, scabrous; primary bristles 12.5-20 mm, noticeably longer than the other bristles. Spikelets 3-8 mm, sessile or pedicellate, glabrous; pedicels to 0.2 mm; lower glumes absent or 1.2-1.4 mm, veinless; upper glumes 0.8-2 mm, 0-1-veined; lower florets sterile; lower lemmas 3-7.7 mm, 3-5(7)-veined; lower paleas absent; upper lemmas 3-6.8 mm, 5-veined; anthers 2.6-3.5 mm. 2n = 54.

Pennisetum macrourum is native to Africa, where it grows along rivers and lake margins. In the Flora region, it is known only from one location in Monterey County, California. Although sometimes recommended as an ornamental grass, the U.S. Department of Agriculture considers it a noxious weed.


7.   Pennisetum alopecuroides (L.) Spreng.
Foxtail Fountaingrass

Plants perennial; cespitose. Culms 30-100 cm, erect; nodes glabrous. Sheaths glabrous, margins ciliate; ligules 0.2-0.5 mm, membranous, ciliate; blades (10)30-60 cm long, 2-8(12) mm wide, flat to folded, glabrous, margins ciliate basally. Panicles all terminal, 6-20 cm long, 20-53 mm wide, fully exerted from the sheaths, erect, green to brown, deep purple, or stramineous to creamy-white; rachises terete, with pubescent hairs. Fascicles 9-16 per cm; fascicle axes 1.5-5.6 mm, with a stipelike base of 1-5.6 mm and 1(2) spikelet(s); outer bristles 13-19, 0.8-15.6 mm; inner bristles 7-10, 11.2-30 mm, scabrous; primary bristles 26.7-35 mm, scabrous, usually not noticeably longer than the other bristles. Spikelets 5.5-8.4 mm, sessile or subsessile, glabrous; pedicels to 0.1 mm; lower glumes 0.2-1.4 mm, veinless; upper glumes 2-4.9 mm, to 1/2 as long as the spikelet, 1-5-veined, acute to broadly acute; lower florets sterile; lower lemmas 4.9-8.1 mm, 7-9(10)-veined; lower paleas absent; upper lemmas 5.2-7.6 mm, 5-7-veined, acuminate; anthers 3, 3-4.5 mm. 2n = 18.

Pennisetum alopecuroides is native to southeast Asia. It is frequently grown as an ornamental in the Flora region.


8.   Pennisetum latifolium Spreng.
Uruguay Fountaingrass

Plants perennial; cespitose. Culms 1.5-3 m, erect; nodes pubescent.Sheaths pubescent or scabrous, margins ciliate; ligules 1.3-2 mm; blades 30-75 cm long, 19-45 mm wide, flat, glabrous, pseudopetiolate. Panicles terminal on the culms and axillary in the upper leaf sheaths, 2.2-9.5 cm long, 10-15 mm wide, fully exerted from the sheaths, flexible, drooping, green to stramineous; rachises terete, scabrous or sparsely pubescent. Fascicles5-13 per cm; fascicle axes about 0.3 mm, with 1(2) spikelet(s); outer bristles 8-33, 1.1-11 mm, brittle; inner bristles absent; primary bristles (11.5)15.7-26.5 mm, scabrous, noticeably longer than the other bristles. Spikelets 4-7 mm, sessile; lower glumes 1.2-2.2 mm, 1(2)-veined, scabridulous and ciliolate distally; upper glumes 1.8-3.3 mm, 3-veined, margins ciliolate; lower florets sterile; lower lemmas 4.8-6.8 mm, 5-8-veined; lower paleas absent; upper lemmas 4.6-5.5 mm, 5-veined; upper paleas 2-3-veined; anthers1.2-1.5 mm. Caryopses 2.5-2.8 mm long. 2n = 36.

Pennisetum latifolium is native to South America. It is occasionally grown as an ornamental in the Flora region.


9.   Pennisetum polystachion (L.) Schult.
Mission Grass

Plants annual or perennial; cespitose from a hard, knotty base. Culms 30-200 cm, erect, branching; nodes glabrous. Sheaths glabrous, margins ciliate; ligules 1.5-2.7 mm; blades 15-55 cm long, 4-18 mm wide, flat, glabrous or pubescent. Panicles terminal, 10-25 cm long, 15-30 mm wide, fully exerted from the sheaths, erect to drooping, white, yellow, light brown, or pink to deep purple; rachises terete, scabrous. Fascicles 33-45 per cm, disarticulating at maturity; fascicles axes 0.2-0.5 mm, with 1 spikelet; outer bristles 13-30, 1.3-5 mm, scabrous; inner bristles 6-14, 4.3-11.5 mm, long ciliate; primary bristles 14-25 mm, long-ciliate, noticeably longer than the other bristles. Spikelets 3-4.5 mm, sessile; lower glumes absent or to 2 mm, veinless; upper glumes 3-4.5 mm, glabrous, 5-7-veined, 3-lobed; lower florets sterile or staminate; lower lemmas 3-3.9 mm, 5-7-veined, apices lobed; lower paleas 2.9-3.7 mm; anthers absent or 1.7-2 mm; upper florets disarticulating at maturity; upper lemmas 1.7-3 mm, coriaceous, shiny, 5-veined, apices ciliate; anthers 1.3-2.1 mm. Caryopses about 1.7 mm, concealed by the lemma and palea at maturity. 2n = 18, 36, 45, 48, 52, 53, 54, 56, 78.

Pennisetum polystachion is a polymorphic, weedy African species that has become established in the tropics and subtropics, including Florida. The U.S. Department of Agriculture considers it a noxious weed. Only Pennisetum polystachion subsp. setosum (Sw.) Brunken has been found in the Flora region. It differs from P. polystachion (L.) Schult. subsp. polystachion as indicated in the key below.

1
Plants annual, usually profusely branching; fascicles white, pink, red, or deep purple ..... subsp. polystachion
Plants perennial, usually sparingly branched; fascicles yellow, light brown, or purplish ..... subsp. setosum


10.   Pennisetum pedicellatum Trin.
Hairy Fountaingrass

Plants usually annual, occasionally perennial; cespitose. Culms 40-150 cm, erect, branching; nodes glabrous. Sheaths glabrous, margins ciliate; ligules 1-2 mm; blades 6-30 cm long, 4-15 mm wide, flat, pubescent, basal margins ciliate. Panicles terminal and axillary, (5)8-19 cm long, 30-35 mm wide, erect, pink to purple; rachises terete, puberulent at the base. Fascicles 14-15 per cm, disarticulating at maturity; fascicle axes 1.5-2.5 mm, with (1)2-5 spikelets; outer bristles 10-20, 1.2-2 mm, scabrous; inner bristles 40-90, 2.2-14 mm, long ciliate; primary bristles 15-25 mm, long-ciliate, noticeably longer than the other bristles. Spikelets 3.4-4.8 mm; pedicels 0.5-3.5 mm; lower glumes 1.2-2.4 mm, 0-1-veined; upper glumes 3.4-4.8 mm, glabrous, 5-veined; lower florets staminate or sterile; lower lemmas 3.1-4 mm, 5(6)-veined; lower paleas 2.5-3.5 mm; anthers 3, 2.2-2.5 mm; upper florets disarticulating at maturity; upper lemmas 2-2.7 mm, coriaceous, smooth, shiny, 5-veined, margins glabrous, apices ciliate; anthers 1.5-2.5 mm. Caryopses about 1.7 mm, concealed by lemma and palea at maturity. 2n = 24, 30, 32, 35, 36.

Pennisetum pedicellatum is native to Africa. It now grows in many other areas, including Florida. The U.S. Department of Agriculture considers it a noxious weed.


11.   Pennisetum villosum R. Br. ex Fresen.
Feathertop

Plants perennial; rhizomatous. Culms 16-75 cm, erect; nodes glabrous. Sheaths glabrous, margins ciliate; ligules 1-1.3 mm; blades 5-40 cm long, 2-4.5 mm wide, flat to folded, glabrous, pubescent, or scabrous, margins ciliate or glabrous basally. Panicles terminal, 4-11.5 cm long, 50-75 mm wide, fully exerted from the sheaths, erect, white; rachises terete, pubescent (basally). Fascicles 7-11 per cm; fascicle axes 1.5-2.5 mm, with 1-4 spikelets; outer bristles (0)1-8, 1-13.5 mm; inner bristles 23-41, 13-50.5 mm, densely plumose; primary bristles 40-50 mm, ciliate, usually not noticeably longer than the other bristles. Spikelets 9-12 mm, glabrous; pedicels 0.1-0.4 mm; lower glumes 0.3-1.3 mm, veinless; upper glumes 2.5-5.2 mm, 1(3)-veined; lower florets staminate or sterile; lower lemmas 7.5-10.5 mm, 7-9(10)-veined; lower paleas absent or 5.5-8.5 mm; anthers absent or 3.8-4.5 mm; upper lemmas 9-11 mm, 7-veined, apices scabridulous; anthers 3.5-5 mm. Caryopses concealed by the lemma and palea at maturity. 2n = 45.

Pennisetum villosum is native to Ethiopia, northern Somalia, and the Arabian Peninsula. It is grown as an ornamental in the Flora region.


12.   Pennisetum ciliare (L.) Link
Buffel Grass

Plants perennial; cespitose from a hard, knotty base, with or without rhizomes. Culms 10-150 cm, erect, sometimes branching at the aerial nodes, glabrous, sometimes scabrous beneath the panicle; nodes glabrous. Leaves green or glaucous; sheaths glabrous or pubescent, margins ciliate; ligules 0.5-3 mm, membranous, ciliate; blades 3-50 cm long, 2-13 mm wide, flat, glabrous or pubescent, margins ciliate or glabrous basally. Panicles 2-20 cm long, 4-35 mm wide, fully exerted from the sheaths, erect, green, brown, brown-purple, or dark purple; rachises terete, scabrous. Fascicles 11-37 per cm, disarticulating at maturity; fascicle axes 0.2-1.5 cm, with 1-12 spikelets; outer bristles 16-89, 0.3-11.7 mm, many exceeding the spikelets; inner bristles 7-20, 3.8-13.8 mm, fused to 1/4 of their length, flattened, grooved, ciliate; primary bristles 10.5-23 mm, long-ciliate, noticeably longer than the other bristles. Spikelets 2.5-5.6 mm, sessile, glabrous; lower glumes 1-3 mm, 0-1-veined; upper glumes 1.3-3.4 mm, about 1/2 as long as the spikelet, (0)1-3-veined; lower florets staminate or sterile; lower lemmas 2.5-5.3 mm, 3-7-veined; lower paleas absent or 2.5-5 mm; anthers absent or about 1.4 mm; upper florets not disarticulating at maturity; upper lemmas 2.2-5.4 mm, (3)5(6)-veined, margins glabrous; anthers 1.4-2.7 mm. Caryopses 1.2-1.9 mm long, 0.4-1 mm wide, concealed by the lemma and palea at maturity. 2n = 36 [B. Valdés, R. Parra, A.M. Sánchez, and M.D. Díaz. 1999. Números cromosómicos de plantas de Marruecos, IV. Lagascalia 21:235-240], 45.

Pennisetum ciliare is native to Africa, western Asia, and India. It now grows throughout the warmer, drier regions of the world, often as a forage crop, and is established in much of southern Texas. It is sometimes included in Cenchrus, based solely on the fusion of its bristles.


13.   Pennisetum setigerum (Vahl) Wipff
Birdwood Grass

Plants perennial; cespitose from a hard, knotty base, without rhizomes. Culms 5-100 cm, erect, sometimes branching, mostly glabrous but sometimes scabrous beneath the panicle; nodes glabrous. Leaves green; sheaths glabrous or pubescent, margins ciliate; ligules 0.6-1.2 mm, membranous, ciliate; blades 2-45 cm long, 2.5-7 mm wide, flat, glabrous or pubescent, margins ciliate or glabrous basally. Panicles 2-13.8 cm long, 4-11 mm wide, erect, green or dark purple; rachises terete, scabrous. Fascicles 11-24 per cm, disarticulating at maturity; fascicle axes 0.2-1.1 mm, with 1-12 spikelets; outer bristles 10-62, 0.1-1.8 mm, not exceeding the spikelets; inner bristles 6-32, 1.2-5 mm, ciliate, fused for 1/3-1/2 their length; flattened, grooved; primary bristles 2.9-6.5 mm, ciliate, not noticeably longer than the other bristles. Spikelets 3.1-5.3 mm, sessile, glabrous; lower glumes 1-2.5 mm, 0-1-veined; upper glumes 1.5-3.4 mm, (0)1-3-veined, about 1/2 as long as the spikelet; lower florets staminate or sterile; upper florets not disarticulating at maturity; lower lemmas 2.7-5.3 mm, 3-7-veined; lower paleas absent or 2.5-4.5 mm; anthers absent or 0.9-3 mm; upper lemmas 2.8-5 mm, 3-5-veined; anthers 3, 2-3.2 mm. Caryopses 1.2-1.8 mm long, 0.4-1 mm wide. 2n = 34, 36, 37, 54, 72.

Pennisetum setigerum is grown as a forage grass in the southern United States, but is not known to be established in the Flora region. It is sometimes included in Cenchrus, based solely on the fusion of its bristles.


14.   Pennisetum flaccidum Griseb.
Humalayan Fountaingrass

Plants perennial; rhizomatous. Culms 50-200 cm, erect, branching, smooth or scabrous beneath the panicle; nodes shortly pubescent or glabrous. Leaves green, sometimes glaucous; sheaths glabrous, margins ciliate; ligules 1-1.5 mm; blades 34-44 cm long, 5-10 mm wide, flat, glabrous or pubescent, margins ciliate or glabrous basally. Panicles all terminal, 8-17 cm long, 12-28 mm wide, erect, white; rachises scabrous below, sometimes puberulent above. Fascicles 6-15 per cm; fascicle axes 0.6-3.1 mm, with 1-6 spikelets; outer bristles 20-60, 0.8-12.3 mm; inner bristles 3-7, 5.5-16.5 mm, flattened, neither grooved nor fused, ciliate; primary bristles 12.9-22.5 mm, ciliate, noticeably longer than the other bristles. Spikelets 5.2-6.7 mm; pedicels 0.1-0.5 mm; lower glumes 0.9-1.8 mm, 0-1-veined; upper glumes 2.6-4.2 mm, 1-5-veined; lower florets staminate; lower lemmas 5.1-6.4 mm, 5(6)-veined; lower paleas 4.5-5.3 mm; anthers 2.8-3.3 mm; upper florets not disarticulating at maturity; upper lemmas 5-5.8 mm, 5(6)-veined; upper paleas with a bifid apex, teeth 0.1-0.2 mm; anthers 2.6-3.2 mm. Caryopsesconcealed by the lemma and palea at maturity. 2n = 18, 36, 45.

Pennisetum flaccidum is native to central Asia. Although grown primarily as an ornamental, it is also used for forage in the Flora region. It is sometimes sold, incorrectly, as P. incomptum Nees ex Steud. [= P. ciliare].


15.   Pennisetum setaceum (Forssk.) Chiov.
Tender Fountaingrass

Plants perennial, or annual in temperate climates; cespitose. Culms 40-150 cm, erect, pubescent beneath the panicle; nodes glabrous. Leaves green, sometimes glaucous; sheaths glabrous, margins ciliate; ligules 0.5-1.1 mm; blades 20-65 cm long, 2-3.5 mm wide, convolute or folded, scabrous, midvein noticeably thickened. Panicles (6)8-32 cm long, 40-52 mm wide, erect or arching, pink to dark burgundy; rachises pubescent. Fascicles 8-10 per cm; fascicle axes 2.3-4.5 mm, with 1-4 spikelets; outer bristles 28-65, 0.9-19 mm; inner bristles 8-16, 8-27 mm, ciliate; primary bristles 26.5-34.3 mm, ciliate, noticeably longer than the other bristles. Spikelets 4.5-7 mm, sessile or pedicellate; pedicels to 0.1 mm; lower glumes absent or to 0.3 mm, veinless; upper glumes 1.2-3.6 mm, (0)1-veined; lower florets usually sterile, sometimes staminate; lower lemmas 4-6 mm, 3-veined, acuminate, midvein excurrent to 0.7 mm; lower paleas usually absent, if present, to 4.4 mm; anthers absent or 2.3-2.4 mm; upper lemmas 4.5-6.7 mm, attenuate, 5-veined, midvein excurrent to 0.7 mm, margins glabrous; anthers 2.1-2.7 mm. 2n = 27.

Pennisetum setaceum is a desert grass native to the eastern Mediterranean region. It is a popular ornamental throughout the southern United States, but it is also an invasive weed.


16.   Pennisetum orientale Willd.ex Rich.
White Fountaingrass

Plants perennial; rhizomatous. Culms 50-200 cm, erect, pubescent beneath the panicle; nodes pubescent. Leaves green or glaucous; sheaths antrorsely scabridulous, mostly glabrous, margins ciliate; ligules 1-1.7 mm; blades 25-50 cm long, 3-9 mm wide, flat, antrorsely scabridulous, glabrous or pubescent, margins ciliate or glabrous basally, midvein not noticeably thickened. Panicles 11.5-37.3 cm long, 35-50 mm wide, fully exerted from the sheaths, erect to slightly arching, white (sometimes purplish-tinged); rachises terete, pubescent. Fascicles 5-12 per cm; fascicle axes 1-6 mm, with 1-10 spikelets; outer bristles 0-24, 0.8-9.6 mm, terete, scabrous; inner bristles 6-20, 5.6-17.5 mm, ciliate; primary bristles 12.2-23.8 mm, ciliate, noticeably longer than the other bristles. Spikelets 5.6-6.7 mm; pedicels 0.1-0.2 mm; lower glumes 1-2.2 mm, veinless; upper glumes 3.1-5.5 mm, 1-3-veined; lower florets staminate; lower lemmas 5.2-6.5 mm, 4-6-veined; lower paleas 3.8-5 mm; anthers 2.3-3 mm; upper florets not disarticulating at maturity; upper lemmas 5.2-6.2 mm, margins glabrous, 5-veined; upper paleas bifid, teeth 0.3-0.8 mm; anthers 1.9-2.9 mm. Caryopses concealed by the lemma and palea at maturity. 2n = 18, 27, 36, 45, 54.

Pennisetum orientale is native from North Africa to India. It is grown as an ornamental in the Flora region, but has potential as a forage species.


17.   Pennisetum advena Wipff & Veldkamp
Purple Fountaingrass

Plants perennial, or annual in temperate climates; cespitose. Culms 1-1.5 m, erect, sometimes branching above, pubescent beneath the panicle; nodes glabrous. Leaves burgundy (rarely green); sheaths glabrous, margins ciliate; ligules 0.5-0.8 mm; blades 33-52 cm long, 6-11 mm wide, flat, antrorsely scabridulous, margins ciliate basally, midvein not noticeably thickened. Panicles 23-32 cm long, 30-58 mm wide, fully exerted from the sheaths, flexible, drooping, burgundy (rarely pale or whitish-green); rachises terete, pubescent. Fascicles 10-17 per cm, disarticulating at maturity; fascicle axes 1-2 mm, with 1-3 spikelets; outer bristles 43-68, 1.2-18.5 mm, terete, scabrous; inner bristles 4-10, 11.7-25 mm, long-ciliate; primary bristles 21.3-33.6 mm, ciliate, noticeably longer than the other bristles. Spikelets 5.3-6.5 mm; pedicels 0.1-0.3 mm; lower glumes 0.5-1 mm, veinless; upper glumes 1.9-3.6 mm, 0-1-veined; lower florets staminate; lower lemmas 4.7-6.1 mm, 5(6)-veined; lower paleas 4.5-5 mm; anthers 2-2.5 mm; upper florets not disarticulating at maturity; upper lemmas 5.2-6.1 mm, 5-veined; anthers 2.5-2.7 mm. Caryopses concealed by the lemma and palea at maturity. 2n = 54.

The origin of Pennisetum advena is uncertain. It is frequently cultivated as an ornamental, usually being sold as Pennisetum setaceum 'Rubrum'.


18.   Pennisetum petiolare (Hochst.) Chiov.

Plants annual; tufted, rooting at the lower nodes. Culms 70-200 cm, slender, erect, branching; nodes glabrous. Sheaths glabrous; ligules 0.7-1 mm, of hairs; blades 3.5-30 cm long, 8-24 mm wide, flat, sparsely pubescent, abruptly rounded or cordate basally; lower blades with a 0.5-13 cm pseudopetiole. Panicles terminal and axillary, 3-8 cm, on long peduncles, fully exerted from the sheaths; rachises terete, hispid; disarticulation beneath the primary bristles, fascicle axes persistent. Fascicles 14-24 per cm; fascicle axes 0.4-0.6 mm, with 1 spikelet, outer and inner bristles absent; primary bristles 3.8-30 mm, scabrous. Spikelets 2.5-3.2 mm, sessile, green to purple. Glumes veinless, truncate or emarginate; lower glumes 0.2-0.3 mm; upper glumes 0.3-0.4 mm; lower florets sterile; lower lemmas 2.5-3.2 mm, strigulose above, 5-7-veined; lower paleas absent; upper lemmas 2.3-3 mm, sparsely puberulent, 5-veined; anthers 3, 1.5-1.9 mm. 2n = unknown.

Pennisetum petiolare is native to northern Africa, where it grows in disturbed habitats. The only collection in the Flora region is from Ames, Iowa, where it grew from fallen bird seed. It is not known to be established anywhere in the region.