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sixweeks three-awn, three awn

Kearney's three-awn, red three-awn, slender three-awn, slimspike threeawn, southeastern slim-spike three-awn

Habit Plants short- to long-lived annuals. Plants annual.
Culms

(3)10-50(80) cm, often highly branched above the base.

15-65 cm, erect to spreading, often geniculate-based, sometimes nearly prostrate, usually much-branched.

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.

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

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.

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

crowded.

widely spaced to 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.

2-11 mm, subequal, 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° at the 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

= 22.

= unknown.

Aristida adscensionis

Aristida longespica

Distribution
from FNA
AZ; CA; CO; KS; MD; MO; NE; NM; NV; NY; OK; SC; TX; UT; HI; PR; Virgin Islands
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; AZ; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; SD; TN; TX; VA; VT; WA; WI; WV; ON
[WildflowerSearch map]
[BONAP county map]
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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Central awns 8-27 mm long, lateral awns usually 6-18 mm long
var. geniculata
1. Central awns 1-14 mm long and/or lateral awns usually 0-5 mm long
var. longespica
Source FNA vol. 25, p. 330. FNA vol. 25, p. 328.
Parent taxa Poaceae > subfam. Aristidoideae > tribe Aristideae > Aristida Poaceae > subfam. Aristidoideae > tribe Aristideae > Aristida
Sibling taxa
A. arizonica, A. basiramea, A. californica, A. condensata, A. desmantha, A. dichotoma, A. divaricata, A. floridana, A. gypsophila, A. gyrans, A. havardii, A. lanosa, A. longespica, A. mohrii, A. oligantha, A. palustris, A. pansa, A. patula, A. purpurascens, A. purpurea, A. ramosissima, A. rhizomophora, A. schiedeana, A. simpliciflora, A. spiciformis, A. stricta, A. ternipes, A. tuberculosa
A. adscensionis, A. arizonica, A. basiramea, A. californica, A. condensata, A. desmantha, A. dichotoma, A. divaricata, A. floridana, A. gypsophila, A. gyrans, A. havardii, A. lanosa, A. mohrii, A. oligantha, A. palustris, A. pansa, A. patula, A. purpurascens, A. purpurea, A. ramosissima, A. rhizomophora, A. schiedeana, A. simpliciflora, A. spiciformis, A. stricta, A. ternipes, A. tuberculosa
Subordinate taxa
A. longespica var. geniculata, A. longespica var. longespica
Synonyms A. interrupta, A. bromoides, A. adscensionis var. modesta
Name authority L. Poir.
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