sixweeks threeawn, more...
[Aristida adscensionis f. modestina Hack., more]
Plants short- to long-lived annuals. Culms (3)10-50(80) cm, often
highly branched above the base. Leaves 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. Inflorescences
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. Spikelets
crowded. Glumes 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. 2n = 22.
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 A. 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
Plant: Annual grass 10-30 cm; inflorescence narrow and spikelike, often with a purplish color; spikelets with one floret, unequal glumes; lemma elongated into a twisted awn column, apex bearing three awns 5-15 mm long. Notes: This is a very widespread species in the drier areas of the world. Becauseý of the numerous morphological forms many infraspecific names have been proposed. However, many of the distinctive forms are connected by intergrading forms, and for this reason no infraspecific taxa are recognized in this Catalogue pending a world-wide revision of this taxon. References: Delta World Grasses
A chiefly tropical sp. with the awns flat at the base, the central one 8-15 mm, the first glume half to two-thirds as long as the second, is rarely adventive in our range.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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