Culms 40-150 cm, erect; nodes glabrous, uppermost node often concealed
within the sheaths. Leaves cauline, mostly glabrous; sheaths with
a white, powdery bloom; ligules 1-2.2 mm; blades 10-20 cm long,
3-6(8) mm wide, flat to folded. Panicles 4.5-15 cm, lanceolate; rachises
with numerous branches; branches shorter than the rachises, erect-appressed,
lacking axillary pulvini; rame internodes with a central groove about as
wide as the margins, margins densely villous, hairs 4-6 mm, obscuring the spikelets.
Sessile spikelets 2.5-4 mm long, 0.6-0.8 mm wide, narrowly ovate; lower
glumes glabrous or sparsely short-pilose, lacking a dorsal pit; awns
absent or to 6 mm; anthers 0.5-1.5 mm. Pedicellate spikelets shorter
than the sessile spikelets, sterile. 2n = 60.
Bothriochloa exaristata grows in heavy soils of fields and roadsides of
the Gulf coastal prairie, at 2-150 m, as well as in coastal areas of southern
Brazil and adjacent Argentina, and inland along the Rio Pilcomayo to Paraguay.
It has been reported from Los Angeles County, California. When growing in dense
grassland thickets, B. exaristata has rather spindly basal growth, but
branches abundantly from the middle and upper nodes.