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

1062 POACEAE/SORGHUM
(Kellogg 2000a). It has sometimes been treated as a subgenus within Sorghum (e.g., Garber
1950). However, recent molecular evidence (Spangler et al. 1999) supports their separation. Some
species are important pasture grasses. � However, young plants represent a cyanide risk for
grazing animals (the mechanism is similar to that seen in Sorghum), but “actual livestock losses
are rare” (Burrows & Tyrl 2001). (Name from Sorghum and the Latin suffix astrum, ‘a poor imitation
of,’ for its resemblance to the genus Sorghum—Dávila Aranda & Hatch 2003) (subfamily
Panicoideae, tribe Andropogoneae)
REFERENCES: Garber 1950; Celarier 1958; Hall 1982; Dávila 1988, 1991; Spangler et al. 1999; Dávila
Aranda & Hatch 2003.
1. Awns of lemmas mostly 23–40 mm long, usually twice-geniculate; spikelets at maturity usually
dark brown; rhizomes not present _____________________________________________________ S. elliottii
1. Awns of lemmas usually 12–22 mm long, once-geniculate; spikelets at maturity light brown to
straw-colored or yellowish; short scaly rhizomes present ____________________________________ S. nutans
Sorghastrum elliottii (C. Mohr) Nash, (for Stephen Elliott, 1771–1830, Carolinian botanist), SLEN-
DER INDIAN GRASS, LONG-BRISTLE INDIAN GRASS. Plant not rhizomatous; culms usually 0.8–1.8 m
tall; ligule 1–5 mm long; panicle narrow, looser than in S. nutans, sparsely-flowered, 15–30 cm
long, dark colored; pedicels flexuous, often recurved; spikelets usually 5.5–7 mm long. Sandy
wooded areas; widespread in East TX w to Dallas (Reverchon, 1876), Fannin (Talbot property)
(BRIT), Bexar, and Hays (Turner et al. 2003) cos.; also n Gulf Prairies and Marshes; se U.S. from
MD s to FL w to OK and TX. Sep–Nov.
Sorghastrum nutans (L.) Nash, (nodding), YELLOW INDIAN GRASS, INDIAN REED. State grass of
Oklahoma (S. Barber, pers. comm.). Rhizomes short, scaly; culms erect, to 2.5 m tall; ligule 2–6
mm long; panicles loosely contracted, to 30 cm long, yellowish to yellowish-brown; spikelets
usually 6–8 mm long. Prairies, savannahs, open woodlands; throughout TX; se Canada and
throughout e 2/3 of the U.S. w to WY and AZ. Sep–Nov. [S. avenaceum (Michx.) Nash] This species
was one of the dominants in the original tall grass prairie; it is considered one of the “big four”
tall grasses along with Andropogon gerardii, Panicum virgatum, and Schizachyrium scoparium.
It is an important forage grass and an indicator of good range conditions. INDIAN GRASS is recognizable
in the field in vegetative condition by the bluish green foliage. The yellowish inflorescences
can be quite showy in the fall, particularly in bright sunlight. The reproductive biology
of this species was studied by McKone et al. (1998); it was found to be very unusual in allocating
more resources to male reproduction (pollen production) than to female reproduction (seed
production). m/299
SORGHUM Moench SORGHUM
Robust annuals or perennials; culms erect; ligule a ciliate membrane; leaf blades flat; inflorescence
an open or contracted panicle; spikelets in pairs, one sessile and fertile, the other
pedicelled and staminate; disarticulation below sessile spikelets so that associated pedicel and
section of inflorescence branch fall with spikelet, sometimes also disarticulating below pedicellate
spikelets, or in cultivated taxa the spikelets not disarticulating or doing so tardily; sessile
spikelet 2-flowered, the lower floret reduced to a lemma, the upper floret fertile, with lemma
awned (awn twisted and geniculate) or awnless.
AA mainly Old World genus of 25 species (Dillon et al. 2001; Barkworth 2003j) (Mexico, 1 species),
including S. bicolor, SORGHUM, MILO, the world’s fourth most important cereal after WHEAT,
CORN, and RICE. This species, which is more tolerant of drought than most cereals, is of particular
importance in Africa and Asia where it feeds millions of people (Heiser 1990). Some species
(S. �almum, S. bicolor, S. halepense) are considered significant weeds (Watson & Dallwitz 1992).
Hybridization is common in the genus. Preliminary molecular evidence (Spangler et al. 1999,