Plants cespitose, upper portion dense, oblong to oblanceolate or obpyramidal.
Culms 20-250 cm; internodes green, sometimes glaucous; branches
mostly erect, straight. Sheaths usually scabrous, sometimes smooth; ligules
0.6-2.2 mm, sometimes ciliate, cilia to 0.9 mm; blades 13-109 cm long,
2.9-9.5 mm wide, glabrous or sparsely to densely pubescent, hairs usually spreading,
rarely appressed. Inflorescence units 10-600 per culm; subtending
sheaths (2.0)2.9-4.4(6.5) cm long, (1.5)2.3-3.4(4.4) mm wide; peduncles
(1)6-14(60) mm, with 2(4) rames; rames (1)1.7-2.5(3.5) cm, exserted or
not at maturity, pubescence sparse basally and increasing in density distally
within each internode. Sessile spikelets 3-5 mm; callus hairs
1-2.5 mm; keels of lower glumes sometimes scabrous below midlength, usually
scabrous distally; awns 6-19 mm; anthers 1(3), 0.5-1.5 mm, yellow,
red, or purple. Pedicellate spikelets vestigial or absent, sterile. 2n
= 20.
Andropogon glomeratus hybridizes with both A.
longiberbis and A. virginicus.
Some of its varieties are morphologically similar to the latter species.
Plants usually oblong in the upper portion, sometimes cylindrical. Culms
1-2 m; internodes not glaucous. Sheaths scabrous; ligules
ciliate or not, cilia to 0.3 mm; blades green, usually pubescent. Subtending
sheaths of inflorescence units (2)2.4-3.1(4) mm wide; peduncles 2-5(8)
mm; rames usually 1.7-2.8 cm, not exserted at maturity. Keels of lower
glumes usually smooth below midlength, scabrous distally; anthers
often retained within the spikelets.
Andropogon glomeratus var. hirsutior grows in ditches, swales,
bogs, flatwoods, and savannahs of the southeastern coastal plain, often forming
very large populations in cleared, low ground.
Plants oblanceolate to obpyramidal in the upper portion. Culms
to 2.5 m, but as short as 20 cm in poor soils; internodes not glaucous.
Leaf sheaths usually smooth; ligules ciliate, cilia 0.2-0.9 mm;
blades green, smooth or pubescent. Subtending sheaths of inflorescence
units (2)2.9-4.3(5.2) cm long, 1.5-3 mm wide; peduncles (2)8-15(40)
mm; rames 1.3-3 cm, exserted. Keels of lower glumes usually smooth
below midlength, scabrous distally; anthers often retained within the
spikelets.
Andropogon glomeratus var. pumilus is weedy and grows in disturbed,
wet or moist sites. It is abundant and widespread, extending from the southern
United States through Central America to northern South America.