Plants annual. Culms 15-65 cm, erect to spreading, often geniculate-based,
sometimes nearly prostrate, usually much-branched. Leaves cauline; sheaths
shorter than the internodes, not disintegrating into threadlike fibers at maturity,
glabrous or sparsely pilose, hairs on the throat sometimes to 5 mm; collars
glabrous; ligules about 0.5 mm; blades 5-14 cm long, 1-2 mm wide,
flat to loosely involute, light green. Inflorescences usually paniculate,
occasionally racemose or spicate, 6-22 cm long, 1-4(6) cm wide; nodes
glabrous or with straight hairs, hairs to 0.3 mm; primary branches 1-4
cm, appressed to erect, rarely somewhat spreading distally, without axillary
pulvini, with 2-5 spikelets per branch. Spikelets widely spaced to crowded.
Glumes subequal, 2-11 mm, 1-veined, acuminate, unawned or awned, awns
to 1 mm; calluses less than 1 mm; lemmas 2.5-10 mm, gray to dark
purplish-brown, often horizontally banded or mottled, scabrous-hispid or glabrous,
not beaked, apices only slightly narrowed, junction with the awns not evident;
awns usually unequal, terete and curving up to 100° atthe base, erect
to reflexed distally, not disarticulating at maturity; central awns 1-27
mm; lateral awns absent or to 18 mm, shorter than the central awns; anthers
1 and 0.2-0.3 mm, or 3 and 3-4 mm. Caryopses 3-4 mm, light brown. 2n
Aristida longespica grows along roadsides and in waste places, sandy
fields, and clearings in pine and oak woods of southern Ontario and the eastern
and central United States. The two varieties have a similar geographic range
and are often found growing together.
Annual, 2-5 dm, loosely tufted in small bunches, often branching from the lower nodes; blades flat or involute, 1-2 mm wide, the larger often only 4-8 cm long; panicle ±elongate, to half the length of the plant, very slender, often raceme-like, with appressed or ascending spikelets; axillary panicles much reduced; glumes subequal, 2-11 mm, 1-veined or the first one sometimes obscurely 3-veined; lemmas 3-10 mm; awns terete, to ca 2.5 cm, about equally divergent, or the central one more deflexed. Moist or dry, often sterile or sandy soil; N.H. to s. Ont., Io., and Nebr., s. to the Gulf. Two vars.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.