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Achnatherum robustum - sleepygrass

Scientific Family
Poaceae
Synonyms
Stipa robust
Plant type
Grasses
Riparian
No

Grass Description

Origin
Native
Season
Warm

Dry plains and hills, open woods and forest clearings, and along roadsides.

Plant Community
Disturbed Areas
Interior Chaparral
Montane Conifer Forest
Pinyon Juniper Woodlands
Grasslands
Low elevation
4000
High elevation
8000
Similar species
A. nelsonii

General Description

Stems erect or ascending (curving upward) and growing in dense tufts or clusters, without rhizomes. Leaves mostly below the middle of the stem in 2 vertical ranks on opposite sides of the stem.

Sheath collars are very hairy. The lower nodes of the seedhead are also hairy. Plant is robust, often more than 3 feet tall. Glumes are firm.

Grass type
Perennial bunchgrass
Rhizomes
No
Stolons
No
Clump Diameter 2 ft or more
No
Bushy - highly branched
No
Height with Seedheads
Greater than 36 inches
Seedhead Structure
Branched - contracted
Seedhead droops
No
First bloom month
June
Last bloom month
September

Flower Characteristics

Flowers per Spikelet
One-flowered
Spikelets One-Sided
No
Awns
Greater than 1 inch
Three Awns
No
Awns bent
Yes
Flower and Seedhead Notes

Inflorescence a tight, contracted panicle, with 1 spike or cluster per stem. Awns 3/4 to 1-1/2 inches long or longer, twisted like a corkscrew, and twice geniculate (bent twice).

Vegetative Characteristics

Blade is hairy
No
Blade margins white
No
Blade cross-section
Flat
Involute – rolled inward on upper surface

Linear leaf blades 1/8 to 3/8 inch wide and hairless. Leaf blades mostly flat with the margins rolled inward. Bottom surface smooth, top surface roughly ribbed.

Sheath is hairy
No
Tufts of hair top of sheath or collar
Yes
Ligule
Membranous
Auricles
No

Contains diacetone alcohol which can be poisonous to livestock, hence the common name sleepygrass.