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sixweeks three-awn, three awn

Florida threeawn, key west threeawn

Habit Plants short- to long-lived annuals. Plants perennial; cespitose.
Culms

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

70-100 cm, erect, mostly unbranched.

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 mostly longer than the internodes, mostly glabrous, summit with hairs;

collars mostly glabrous, sides usually with straight or wrinkled hairs;

ligules 0.2-0.3 mm;

blades 30-55 cm long, 1-2 mm wide, pale yellow-green, loosely involute, lax, glabrous abaxially, with scattered hairs adaxially.

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.

paniculate, 30-45 cm long, 5-25 cm wide, oblong to ovate;

primary branches single or paired, ascending and somewhat lax to stiffly divergent, with weakly developed axillary pulvini, spikelet-bearing to the base;

lowermost branches to 15 cm.

Spikelets

crowded.

mostly appressed.

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.

purplish-tinged, 1-veined;

lower glumes 10-14 mm;

upper glumes 8-9 mm;

calluses 0.5-0.7 mm;

lemmas 8-12 mm, gray mottled with purple or dark patches, narrowing to a slightly curved and twisted beak, junction with the awns not strongly marked;

awns not disarticulating at maturity;

central awns 10-25 mm, falcate;

lateral awns absent;

anthers 3, about 1 mm, brown.

Caryopses

6-7 mm, chestnut-colored.

2n

= 22.

= unknown.

Aristida adscensionis

Aristida floridana

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
FL
[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 floridana grows in waste places, along road-sides, and on railroad embankments. It is rare in the United States, being known only from Key West and Ramrod Key, Florida. It is more common in the Yucatan Peninsula, Mexico, where it intergrades with Aristida ternipes.

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

Source FNA vol. 25, p. 330. FNA vol. 25, p. 321.
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. 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
Synonyms A. interrupta, A. bromoides, A. adscensionis var. modesta
Name authority L. (Chapm.) Vasey
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