Aristida adscensionis

L.
Common names: Sixweeks threeawn
Synonyms: Aristida interrupta Aristida bromoides Aristida adscensionis var. modesta
Treatment appears in FNA Volume 25. Treatment on page 330.

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 some¬what 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.

Distribution

Puerto Rico, Md., Kans., Okla., Colo., N.Mex., Tex., Utah, Calif., Nebr., N.Y., Pacific Islands (Hawaii), Virgin Islands, S.C., Ariz., Mo., Nev.

Discussion

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.

Selected References

None.

Lower Taxa

None.

"decumbent" is not a number.

... more about "Aristida adscensionis"
3 +  and 1 +
3 cm30 mm <br />0.03 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
Kelly W. Allred +
not disarticulating +
1 (?) +  and 3 (?) +
straight +
ascending +  and spreading +
not evident +
flattened +
keeled +  and rounded +
coiled +, disarticulating +  and twisted +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
straight +
2 cm20 mm <br />0.02 m <br /> (14 cm140 mm <br />0.14 m <br />) +
flat +  and involute +
0.1 cm1 mm <br />0.001 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
spikelike +
well-developed +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
non-radiate +  and radiate +
0.7 cm7 mm <br />0.007 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
Sixweeks threeawn +
10 cm100 mm <br />0.1 m <br /> (50 cm500 mm <br />0.5 m <br />) +
not woody +
Puerto Rico +, Md. +, Kans. +, Okla. +, Colo. +, N.Mex. +, Tex. +, Utah +, Calif. +, Nebr. +, N.Y. +, Pacific Islands (Hawaii) +, Virgin Islands +, S.C. +, Ariz. +, Mo. +  and Nev. +
large +  and small +
thread-like +
capillary +
germination +
pistillate +  and staminate +
sometimes longer +
compressed +  and terete +
subtending +
acuminate +
unequal +
straight +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (3 cm30 mm <br />0.03 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
scabridulous +
0.6 cm6 mm <br />0.006 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
coriaceous +
indistinguishable +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
inconspicuous +
0.4 cm4 mm <br />0.004 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
concealed +  and prominent +
with straight , 0-0.5 mm hairs +  and glabrous +
2 +  and 1 +
concealing +
0 +  and 1/2 +
dry +  and fleshy +
divaricate +  and divergent +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
not prolonged +
not disintegrating +
1 (?) +  and Anatomy (?) +
1 +  and 3 +
triangular +  and dome--shaped +
2 (?) +  and 3 (?) +
Aristida interrupta +, Aristida bromoides +  and Aristida adscensionis var. modesta +
Aristida adscensionis +
Aristida +
species +
membranous +
0.6 cm6 mm <br />0.006 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
annual +  and long-lived +
aquatic +  and terrestrial +
curved +