keys to the vascular plants of east texas - Botanical Research ...

1024 POACEAE/PENNISETUM
relationship of Pennisetum to allied genera (e.g. Cenchrus L.) is unresolved.” Recent molecular
studies suggest Pennisetum is “probably paraphyletic” without the inclusion of Cenchrus
(Gómez-Martínez & Culham 2000). However, until more information is available, we are following
most recent authorities (e.g., Wipff 2003j) in maintaining the traditional circumscription
of Pennisetum. (Latin: penna, a feather, and seta, a bristle, referring to the feathery bristles
around the spikelets) (subfamily Panicoideae, tribe Paniceae)
REFERENCES: Chase 1921; Brunken 1977; Türpe 1983; Webster 1988; Crins 1991; Ramu et al. 1996;
Wipff & Veldkamp 1999; Wipff 2001a, 2003j.
1. Bristles of involucre united at base, forming a small shallow disk 0.5–1.5 mm in diam.; lower
portion of inflorescence axis scabrous ____________________________________________________ P. ciliare
1. Bristles of involucre not united, free to base; lower portion of inflorescence axis pubescent.
2. Inflorescence usually quite dense (so much so that they are not well-flattened on herbarium
specimens), resembling that of a Typha (CAT-TAIL); peduncle stout, usually ca. 3–7 mm wide
just below inflorescence; involucres and spikelets persistent on inflorescence axis even at
maturity (= not disarticulating); bristles of involucre often (but not always) mostly about the
length of the enclosed spikelets, sometimes longer; plants annuals _______________________ P. glaucum
2. Inflorescence not so dense as to be difficult to flatten, usually much smaller than that of a
Typha; peduncle more slender, � 2 mm wide just below inflorescence; involucres and spikelets
readily deciduous from inflorescence axis; bristles longer than the enclosed spikelets,
often much so; plants perennial.
3. Spikelets (7–)9–12(–15) mm long; longest bristles of involucre usually 4–5(–7) cm long;
lemma of lower floret with 7–11 veins; inflorescence 4–10(–12) cm long; leaf blades 2–5
mm wide ___________________________________________________________________ P. villosum
3. Spikelets 4.4–7 mm long; longest bristles of involucre usually less than 3.5(–4) cm long;
lemma of lower floret with 1–6 veins; inflorescence usually 8–37 cm long; leaf blades 2–40
mm wide.
4. Plants usually (1–)2–4+ m tall; leaf blades (4–)12–40 mm wide; inflorescence golden
yellow or dark purple; inflorescence axis straight, erect, with 30–40 spikelet clusters per
cm; ligule 1.5–5 mm long __________________________________________________ P. purpureum
4. Plants 0.5–1.5+ m tall; leaf blades 2–11 mm wide; inflorescence white to greenish white
or pink to dark burgundy; inflorescence axis often � flexuous, erect or arching, with 5–
12 spikelet clusters per cm; ligule 0.5–1.7 mm long.
5. Longest bristles of involucre more than 2.5 cm long; leaf blades 2–3.5 mm wide, convolute
or folded, green, the midvein noticeably thickened; nodes glabrous; inflorescence
pink to dark burgundy; lower glume 0.3 mm or less long or absent __________ P. setaceum
5. Longest bristles of involucre usually less than 2.5 cm long; leaf blades 3–11 mm wide,
flat, green or burgundy, the midvein not noticeably thickened; nodes pubescent; inflorescence
white or greenish white (sometimes purplish tinged); lower glume 1–2.2
mm long _______________________________________________________________ P. orientale
Pennisetum ciliare (L.) Link, (ciliate, fringed with hairs), BUFFEL GRASS. Perennial, usually knotty
at base; culms erect to geniculate-spreading, to 100(–150) cm long; inflorescence 3–10(–20) cm
long, 1–2(–3.5) cm wide, erect, green to brown, brown-purple, or dark purple; spikelet clusters
11–37 per cm of inflorescence axis; bristles of involucre united at base, ca. 4–14(–23) mm long,
purplish, often wavy; spikelets 1–12 per cluster, 2.2–5.6 mm long. Roadsides, disturbed sites;
Brazos, Wilson (BRIT), Caldwell, and McLennan (TAES) cos. in s part of East TX; mainly Gulf
Prairies and Marshes, South TX Plains, Edwards Plateau, and Trans-Pecos; sw U.S. from TX w to
CA, also AL, FL, LA, MS, and MO. Spring–fall. Native of Africa, w Asia, and India. [Cenchrus
ciliaris L.] This species has sometimes been treated as a Cenchrus (see Cenchrus for further discussion),
based on its basally fused bristles. It also closely resembles Setaria in often having
relatively short bristles and no spines, but the spikelet cluster (bristles and spikelet(s)) falls as a