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arrow-feather threeawn

California three-awn, Mojave three-awn

Habit Plants perennial; cespitose, bases knotty, without rhizomes. Plants perennial; sometimes flowering the first year.
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.

10-40 cm, highly branched above the base in age;

internodes glabrous or pubescent, sometimes nearly lanose.

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.

cauline;

sheaths shorter than the internodes, glabrous or puberulent;

collars glabrous or pubescent at the sides;

ligules 0.5-1 mm;

blades usually less than 6 cm long, 0.5-1 mm wide, pale green, involute, glabrous or puberulent abaxially.

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.

paniculate or racemose, 5-10 cm long, 1-2 cm wide, with few spikelets;

rachis nodes glabrous or with straight hairs;

primary branches 1-2 cm, appressed, without axillary pulvini.

Spikelets

appressed.

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.

unequal, 1-2-veined;

lower glumes 4-10 mm;

upper glumes 7-15 mm;

calluses about 1 mm;

lemmas 5-7 mm, purple or mottled, junction of the lemma and awns evident;

awns twisted together basally into a 4-26 mm column, free portions 12-50 mm, those of the central and lateral awns similar in length, curved to arcuate basally, straight and divergent distally, disarticulating at the base of the column at maturity;

anthers 3, about 2 mm long.

Caryopses

3-5 mm, chestnut brown.

2n

= unknown.

= 22.

Aristida purpurascens

Aristida californica

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
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from FNA
AZ; CA
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Discussion

The range of both varieties of Aristida californica extends from the southwestern United States into northwestern Mexico.

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

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
1. Cauline internodes puberulent to nearly lanose
var. californica
1. Cauline internodes glabrous
var. glabrata
Source FNA vol. 25, p. 338. FNA vol. 25, p. 319.
Parent taxa Poaceae > subfam. Aristidoideae > tribe Aristideae > Aristida 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
A. adscensionis, A. arizonica, A. basiramea, 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
Subordinate taxa
A. purpurascens var. purpurascens, A. purpurascens var. tenuispica, A. purpurascens var. virgata
A. californica var. californica, A. californica var. glabrata
Name authority Poir. Thurb.
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