Plants perennial; cespitose and rhizomatous, each rhizome terminating in
a cleistogamous spikelet. Culms to 100 cm, erect. Sheaths sparsely
pilose near the ligules; ligules of lower leaves with a single prominent
tuft of hairs; ligules of upper leaves usually glabrous; blades
to 30 cm long, to 1 cm wide, usually scabrous, occasionally pilose. Panicles
with 3-10(15) racemosely arranged branches, usually most nodes with more than
1 branch; branches 6-10 cm, naked below, with about 4 spikelets per cm
distally. Spikelets with 1 bisexual and 1 sterile floret. Lower glumes
1-2 mm; upper glumes 2-3.5 mm; lower lemmas 4.5-7.5 mm long, about
1 mm wide, linear to narrowly lanceolate, glabrous or the margins sparsely strigose
above, apices acute to acuminate, often bidentate, unawned or awned, awns 6.5-15
mm; sterile florets 1.4-3 mm long, to 0.3 mm wide, awns 2-8 mm. Chasmogamous
caryopses about 4.5 mm long, about 0.8 mm wide; cleistogamous caryopses
to 4 mm long, about 2.5 mm wide. 2n = 40, 80.
Enteropogon chlorideus is native from the southwestern United States through
Mexico to Honduras. The spikelet-bearing rhizomes distinguish Enteropogon
from most other grasses, but they are often missing from herbarium specimens.
Seed set is highest in the cleistogamous spikelets.