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ANDROPOGON L. Bluestem
Plants hermaphroditic, caespitose or rhizomatous, annual or perennial. Culms erect or ascending or decumbent; internodes solid,
glabrous or hairy, terete or flattened; nodes glabrous. Leaves basal and cauline, not distinctly distichous; sheaths terete or with
compressed keels, margins open; auricles absent; ligules membranous or a ciliate membrane; blades flat or folded or involute, linear,
lax, apex acute to acuminate. Panicles of 2 to 7 racemose branches, open, terminal and axillary (few to many inflorescences
per culm), sheaths subtending inflorescence inflated and spathe-like or not inflated and spathe-like; primary branches unbranched,
usually paired or digitate or subdigitate, spreading to ascending, not aromatic, branches hairy or glabrous; pedicels not with a longitudinal
groove, glabrous or hairy, semi-terete. Spikelets usually paired (rarely solitary) or ternate at each inflorescence node, similar and
dissimilar in size and shape, disarticulation below the glumes, dorsiventrally compressed; sessile (or short pediceled) spikelets
fertile, pedicellate (or long pediceled) spikelets staminate or sterile or absent. Pedicellate spikelets well
developed or staminate or sterile or neuter or absent, usually awnless. Sessile spikelets perfect, first glumes 2-keeled
, gland-like depressions or pits absent; abaxial surface flat, smooth, indurate, glabrous or hairy, awnless or awned; second glumes
equal length on first glumes; lower florets staminate or sterile or neuter; lemmas hyaline, apex entire, awnless; paleas absent;
upper florets perfect; hyaline, apex entire to 1/4 cleft (bifid), awned; paleas present (reduced), hyaline. Stamens 1 or 2
or 3; anthers tan or brown. Caryopses laterally or dorsiventrally compressed. Base chromosome number x=10.
A large genus of about 100 species, usually tropical or subtropical. Many taxa are from grasslands or savannahs. Weedy species (A. glomeratus,
A. virginicus) are common in Texas. Big bluestem (A. gerardii) is an important livestock forage in North America.
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