Plants perennial; usually cespitose, occasionally with rhizomes. Culms
30-80(100) cm, erect, unbranched. Leaves mostly basal; sheaths
usually longer than the internodes, mostly glabrous, throat sometimes with hairs,
not disintegrating into threadlike fibers; collars glabrous or with hairs
at the sides; ligules 0.2-0.4 mm; blades 10-25(30) cm long, 1-3
mm wide, usually flat, often curling like wood shavings when mature, glabrous.
Inflorescences spikelike panicles, 10-25 cm long, 1-3 cm wide; nodes
glabrous or with straight, about 0.5 mm hairs; primary branches 2-6 cm,
appressed, without axillary pulvini, with 2-8 spikelets. Glumes 10-15(18)
mm, brownish, acuminate to awned, awns to 3 mm; lower glumes slightly
shorter than to equaling the upper glumes, 1-2-veined; calluses 1-1.8
mm; lemmas 12-18 mm, glabrous, rarely sparsely pilose, terminating in
a 3-6 mm twisted column, junction with the awns not conspicuous; awns
20-35 mm, straight to curved basally, ascending distally, not disarticulating
at maturity; central awns 20-35 mm; lateral awns slightly shorter
than the central awns; anthers 3, 1.3-1.9 mm. 2n = 22.
Aristida arizonica grows in pine, pine-oak, and pinyon-juniper woodlands
from the southwestern United States to southern Mexico.
It may be confused with A. purpurea var. nealleyi,
but differs in having flat, curly leaf blades and longer awns.
FNA 2003, Gould 1980
Common Name: Arizona threeawn Duration: Perennial Nativity: Native Lifeform: Graminoid General: Tufted perennial in small clumps with erect stems 30-80 cm, unbranched; sheaths longer than internodes, rounded, striate with hairs at throats and on either side of the collar; otherwise mostly glabrous. Vegetative: Mostly basal leaves, blades 10-25 cm long, 1-3 mm wide, firm, mostly flat but occasionally folded or involute on drying; ligule a short fringe of hairs less than 0.5 mm. Inflorescence: Spikelike panicles 10-25 cm long, 1-3 cm wide, contracted and with few flowers, nodes glabrous or with straight hairs to 0.5 mm, primary branches 2-6 cm, appressed and bearing 2-8 spikelets; glumes equal, brownish, acuminate to awned with awns to 3 mm, lower glumes slightly shorter than upper glumes, 1-2 veined; lemmas 12-18 mm, glabrous to rarely sparsely pilose, terminating in a 3-6 mm twisted column, junction with awns not conspicuous; awns 20-35 mm, straight to curved basally, ascending distally, not disarticulating at maturity, central awns 20-35 mm, lateral awns slightly shorter than central awns. Ecology: Found on dry rocky sites especially in the oak-pine, pi-on-juniper woodlands from 4,500-8,000 (1372-2438 m); flowers July-October. Distribution: AZ, NM, CO, UT, w TX, n MX Notes: A. arizonica is a perennial three awn with narrow, few-flowered panicles. The spikelets and awns are somewhat large, with awns 2 to 3.5 cm long. There is often a cluster of basal leaves. These can be narrow and straight, but are sometimes distinctively wide, flat, and curled, like ribbon attached to a Christmas present. Can be confused with A. purpurea var. nealleyi but differs in having flat, curly leaf blades and longer awns. Ethnobotany: Unknown Etymology: Aristida is from the Latin arista for awn, while arizonica means of or from Arizona. Synonyms: None Editor: SBuckley 2010, AHazelton 2015