Aristida adscensionis
Aristida tuberculosa
sixweeks three-awn, three awn
seaside threeawn
(3)10-50(80) cm, often highly branched above the base.
(25) 40-100 cm, erect or decumbent to ascending near the base, highly branched above the base;
nodes and internodes glabrous.
cauline, glabrous;
sheaths shorter than the internodes, not disintegrating into threadlike fibers;
ligules 0.4-1 mm;
blades 2-14 cm long, 1-2.5 mm wide, flat to involute.
cauline;
sheaths usually slightly shorter than the internodes, glabrous or pilose;
collars often with a line of tangled hairs;
ligules about 0.5 mm;
blades 8-25 cm long, 2-4 mm wide, light green, flat to loosely involute, glabrous and smooth abaxially, scabridulous adaxially.
panicles, 5-15(20) cm long, 0.5-3 cm wide, often interrupted below;
nodes glabrous or with straight, less than 0.5 mm hairs;
primary branches 1-4 cm, erect to ascending, without axillary pulvini, with 3-8 spikelets.
paniculate, 10-20 cm long, 3-10 cm wide;
rachis nodes glabrous, scabrous, or strigose;
primary branches 1-4 cm, stiffly ascending, with axillary pulvini, with 1-4 spikelets per branch.
crowded.
loosely congested.
unequal, 1-veined, acuminate;
lower glumes 4-8 mm;
upper glumes 6-11 mm;
calluses 0.5-0.8 mm;
lemmas 6-9 mm, slightly keeled, midveins scabrous, junction with the awns not evident;
awns not disarticulating at maturity, flattened and straight to somewhat curved at the base, central rib flanked by equally wide pale wings;
central awns 7-15(20) mm;
lateral awns somewhat shorter, occasionally only 1-2 mm;
anthers 3, 0.3-0.7 mm.
20-30 mm, yellowish-brown, 1-veined, apices narrowing to a 5-10 mm awn;
upper glumes slightly longer than the lower glumes;
calluses 3-4 mm;
lemmas 10-14 mm, dark and mottled at maturity, glabrous or occasionally sparsely pubescent, not beaked, junction of the lemma and awns evident;
awns twisted together basally into a 8-15 mm column, free portions 30-40 mm, those of the central and lateral awns similar in length, strongly curved to arcuate near the base, straight and strongly divergent to reflexed distally, disarticulating at the base of the column at maturity;
anthers 3, about 2.5 mm, brownish.
8-10 mm, dark brown.
= 22.
= unknown.
Aristida adscensionis
Aristida tuberculosa
Aristida adscensionis grows in waste ground, along roadsides, and on degraded rangelands and dry hillsides, often in sandy soils. It is associated with woodland, prairie, and desert shrub communities. Its range extends from the United States south through Mexico and Central America to South America.
Because Aristida adscensionis is highly variable in height, panicle size, and awn development, several varieties have been described. None are recognized here because most of the variation appears to be environmentally induced.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Aristida tuberculosa grows in sandy fields, hills, pinelands, and disturbed areas. Along the Atlantic coastal fringe, it grows on maritime dunes; inland it is associated with xeric pine-oak sandhills. It is generally similar to A. desmantha, but has longer glumes, calluses, and awns. Like A. desmantha, A. tuberculosa is restricted to the United States.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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