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

PENNISETUM/POACEAE 1025
unit as in other Pennisetum species, whereas in Setaria the spikelets disarticulate above the
bristles. BUFFEL GRASS was introduced to the U.S. in the 1940s by the U.S. Soil Conservation Service
and was formally released in San Antonio in 1946 as a forage crop for warm areas of the s
U.S. and Mexico (Tellman 1997). It is resistant to drought and hard grazing (Clayton & Renvoize
1986) but is now a problematic invader of native habitats in some parts of sw North America,
particularly in Sonora, Mexico where it has nearly eliminated cacti and other native plants in
some areas (Tellman 1997). This species can dramatically change the fire ecology of an area—
the large quantities of biomass produced by huge numbers of buffel grass plants contribute to
devastating fires that can threaten whole ecosystems (Tellman 1997; Búuquez-Montijo et al.
2002; Enyedy 2002). Reproduction in this species is predominantly through apomixis (= type
of reproduction in which an embryo is formed without fertilization) (Hignight et al. 1991). I
Pennisetum glaucum (L.) R. Br., (whitened with a coating or bloom), PEARL-MILLET. Coarse annual;
culms 40–100(–300) cm tall; ligule ciliate, 1–5 mm long; leaf blades 8–30(–70) mm wide;
inflorescence 10–40(–200) cm long, quite dense, erect, superficially resembling those of Typha
(CAT-TAIL); spikelet clusters 33–160 per cm of inflorescence axis; involucres and spikelets persistent
on inflorescence axis (this is the only Pennisetum occurring in East TX that displays this
character); bristles of involucres usually 3–6 mm long, sometimes with a single much longer
bristle (rarely bristles all relatively long), the bristles scabrous, the inner ones plumose toward
base; spikelets 1–9 per cluster, 3–7 mm long. A cultivated species probably occurring only as a
transitory waif on roadsides or waste places; Sabine (L. Brown, ASTC) and Harris (Turner et al.
2003) cos.; Hatch (2002) cited vegetational areas 2, 3, and 4; however, we know of no other TX
collections; scattered in the U.S., particularly in the se. Sep–Oct. There is disagreement on the
area of nativity; according to Wipff (2003j), this species is native to Asia; however, Brunken
(1977) indicated that it is native to both Asia and Africa and that the cultivated form is derived
from wild African ancestors. Clayton and Renvoize (1986) also stated that it was probably domesticated
in w Africa ca. 2,000–3,000 years BC. [Chaetochloa glauca (L.) Scribn., Chaetochloa
lutescens (Weigel) Stuntz, Panicum americanum L., Panicum glaucum L., Pennisetum
americanum (L.) Leeke, Pennisetum typhoides of authors, not (Burm.) Stapf & C.E. Hubbard,
Setaria glauca (L.) Beauv.] Due to ambiguity and confusion over type material, there is controversy
concerning the correct name for this species—some authorities (e.g., Yatskievych 1999)
treat it as P. americanum; however, we are following Clayton and Renvoize (1986), Jones et al.
(1999), Kartesz (1999), Wipff and Veldkamp (1999), Hatch (2002), and Wipff (2003j) in treating
it as P. glaucum. Brunken (1977) concluded that the cultivated plant and its wild relatives were
best treated as different subspecies of the same species; as a result, escaped cultivated plants are
in subsp. glaucum. PEARL-MILLET is an important grain crop in dry areas of Africa; it is the most
drought tolerant of the tropical cereal crops (Clayton & Renvoize 1986), with harvests obtained
from as little as 250 mm of annual rainfall (Brunken 1977). In terms of annual production,
Brunken et al. (1977) considered PEARL-MILLET the sixth most important cereal crop worldwide.
This cultivated species has lost the ability to disperse its seeds effectively and thus does not persist
for long without cultivation (Crins 1991). This is presumably the result of artificial selection
for retention of the grains on the inflorescence and thus less loss of the grain crop; similar situations
can be seen in corn, sunflower, and many other plants grown for their seeds. This species
is considered a noxious weed in CO (Kartesz 1999). Under certain conditions, it is known to accumulate
toxic levels of nitrates which can cause poisoning in grazing animals (Burrows &
Tyrl 2001). � � I
Pennisetum orientale Willd. ex Rich., (eastern, from the Orient), WHITE FOUNTAIN GRASS,
LAURISA GRASS. Rhizomatous tufted perennial; culms ca. 40–150+ cm tall, much-branched basally,
erect, the nodes pubescent; ligule membranous, 0.2–1.4(–1.7) mm long; leaf blades 3–11
mm wide; inflorescence ca. 10–25 cm long, rarely longer, often flexuous, white, greenish white,
or sometimes purplish tinged; inner bristles of involucre 6.5–18.5 mm long, plumose; outer