Plant Image
Plant - summer
Granite Mtn - Tr 308
Sue Smith
Yavapai County Native & Naturalized Plants

Aristida purpurea - purple threeawn
Other Common Names: red threeawn

Plant Form:Grass

Family: Poaceae

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Plant image
Plant - summer

Granite Mtn - Tr 308 Sue Smith
Plant image
Plant - summer

Granite Mtn - Tr 308 Sue Smith
  Grass Description -   Glossary of Grass Terminology

Origin: Native    Season: Warm
Habitat Description: Rocky or sandy plains and slopes, frequently on roadsides.
Plant Communities: Interior Chaparral, Semidesert Grasslands, Pinyon Juniper Woodland, Disturbed Areas
Elevation: 3300 - 7000 feet

General Description

Desc: Erect perennial in small dense clumps. with a reddish to purple hue.
Identification notes: Tufts of inwardly rolled 2 to 4 inch long blades; Seedhead narrow, often dense. Branches of the seedhead slender and flexuous; lemma conspicuously scabrous (rough to the touch). Basal portion of awn very short or almost lacking, not twisted, central awns
Grass Type: Perennial bunchgrass  Rhizomes: N  Stolons: N
Large Dense Clump (> 2 feet): N  Bushy (highly branched): N
Height with Seedheads: 12 to 24 inches
Seedhead Structure: Branched - contracted  Seedhead Droops: Y
Flowering Period: May - Sep

Flower Characteristics

Number of Flowers per Spikelet: Multi-flowered  Spikelets One-sided: N
Awns: Greater than 1 inch   Three Awns: Y  Awns Bent: Y

Flower and Seedhead Notes: Seedheads nodding, narrow but rather loose. Glumes are noticeably unequal. Awns are fine and delicate, deeply colored when grains are mature.

Vegetative Characteristics

Blade Hairy: N  Blade with White Margin: N  Blade Cross Section: Involute  
Blade Notes: Blades 2-10 inches long, <1/8 inch wide, tightly rolled inward to flat, usually smooth without hairs, sometimes roughened with stout projections on bottom, gray-green, lax to curled at maturity.
Sheath Hairy: N  Tuft of Hairs Top of Sheath or Collar: Y  Ligules: Membranous
Auricles (Ear-like lobes at base of blades): N
Vegetative Notes: Sheaths shorter or longer than the internodes, smooth without hairs, not disintegrating into threadlike fibers at maturity; collars glabrous, or sparsely pilose at the sides with straight hairs; ligules less than 1/16 inch.

Forage Value: Poor. One of the poorest forages of our common range grasses. Palatability is low, particularly after the plants are mature.

  Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr #C
Prescott, AZ 86305
(928) 445-6590
Version 8.0  
Last Updated: Nov 21, 2021
Content Questions/Comments: Email Mary Barnes  
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