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arrow-feather threeawn

Habit Plants perennial; cespitose, bases knotty, without rhizomes.
Culms

40-100 cm tall, 1-4 mm thick at the base, erect, branching at the base, shoots becoming thickened and somewhat fan-shaped upwards.

Leaves

cauline;

sheaths mostly longer than the internode, mostly or completely glabrous, sometimes pilose, particularly along the margins and at the throat, remaining intact at maturity;

collars glabrous or pilose;

ligules about 0.2 mm;

blades 10-25 cm long, 1-3 mm wide, usually flat, usually lax, sometimes sinuous to curling at maturity, glabrous, pale green, drying brownish.

Inflorescences

paniculate, (15)20-55 cm long, 0.5-2(3) cm wide, often nodding;

nodes glabrous, sometimes scabrous, lower nodes usually associated with more than 2 spikelets;

primary branches 1-5 cm, tightly appressed to loosely ascending, without axillary pulvini, with 1-8 spikelets.

Spikelets

appressed.

Glumes

5-10 mm, lower glumes from 3/4 as long as to 1-4 mm longer than the upper glumes, glabrous or sparsely appressed-pubescent, 1-2-veined, 1-keeled, tan to purplish, unawned or the awns no longer than 1 mm;

calluses 0.4-0.8 mm;

lemmas 4-8 mm, glabrous, mostly light tan or gray, often spotted or banded, beak not twisted, junction with the awns not evident;

awns 8-25 mm, equal or subequal in length, curved, arcuate, or spirally coiled at the base, not disarticulating at maturity;

central awns sometimes thicker than the lateral awns, erect to arcuate-reflexed;

lateral awns straight and erect, ascending, or divergent;

anthers 1 or 3, 1-1.5 mm, brown.

Caryopses

3-5 mm, chestnut brown.

2n

= unknown.

Aristida purpurascens

Distribution
from FNA
AL; AR; CT; DC; DE; FL; GA; IL; IN; KS; KY; LA; MA; MD; MI; MO; MS; NC; NE; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; WI; WV; ON
[WildflowerSearch map]
[BONAP county map]
Key
1. Central awns divaricate to reflexed, about twice as thick at the base as the lateral awns
var. virgata
1. Central and lateral awns divergent, all about the same thickness at the base.
→ 2
2. Lower glumes usually longer than the upper glumes; awns straight or only slightly contorted at the base; blades 1-3 mm wide, often curling
var. purpurascens
2. Lower glumes shorter than or equal to the upper glumes; awns spirally contorted at the base; blades mostly about 1 mm wide, usually not curling
var. tenuispica
Source FNA vol. 25, p. 338.
Parent taxa Poaceae > subfam. Aristidoideae > tribe Aristideae > Aristida
Sibling taxa
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. longespica, A. mohrii, A. oligantha, A. palustris, A. pansa, A. patula, A. purpurea, A. ramosissima, A. rhizomophora, A. schiedeana, A. simpliciflora, A. spiciformis, A. stricta, A. ternipes, A. tuberculosa
Subordinate taxa
A. purpurascens var. purpurascens, A. purpurascens var. tenuispica, A. purpurascens var. virgata
Name authority Poir.
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