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Arrhenatherum elatius - tall oatgrass

Scientific Family
Poaceae
Other common names
false oatgrass
Plant type
Grasses
Riparian
Yes

Grass Description

Origin
Introduced
Season
Cool

Moist or dry meadows, edges of woods, stream sides, rocky outcrops, and disturbed areas such as fields, fence rows and roadsides.

Plant Community
Disturbed Areas
Grasslands
Interior Chaparral
Montane Conifer Forest
Pinyon Juniper Woodlands
Riparian
Low elevation
5000
High elevation
7500

General Description

Tall oatgrass is a loosely-tufted grass with erect, smooth stems 28 to 70 inches tall that are occasionally bulb-like at the base. It is sometimes rhizomatous. It begins growth in early spring and remains green late into the fall. Roots are yellow.

Tall perennials with flat blades. Seedheads are narrow; spikelets are 2-flowered, the lower flower is male, the upper flower has male and female flower parts, disarticulates above the glumes. awn on the first glume twisted, attached below mid-length.

Grass type
Perennial bunchgrass
Rhizomes
Yes
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
Yes
First bloom month
June
Last bloom month
September

Flower Characteristics

Flowers per Spikelet
Multi-flowered
Spikelets One-Sided
No
Awns
1/4 inch to 1 inch
Three Awns
No
Awns bent
Yes
Flower and Seedhead Notes

Seedhead is open and spreading to 3 inches wide, 3 to 12 inches long, green, shiny; sometimes purple-tinged and spikelet-bearing to its base. Lower sterile floret lemma with a stout, twisted or bent awn. Upper fertile floret has a bristle-tipped lemma.

Vegetative Characteristics

Blade is hairy
Yes
Blade margins white
No
Blade cross-section
Flat

There are hairs on the surface of the leaf sheath, but the hairs do not have blisters at their bases. Leaf blades are flat and rough to the touch. They are from 3/8 to 3/4 inches wide.

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

Useful for erosion control on surface mined lands and marginal pastureland. Grown as a forage grass, it yields a palatable hay with high amounts of phosphorus and calcium in its tissues. It does not withstand heavy grazing.