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Agrostis gigantea - redtop

Scientific Family
Poaceae
Synonyms
Agrostis alba
Other common names
redtop bentgrass
black bent
water bentgrass
Plant type
Grasses
Riparian
Yes

Grass Description

Origin
Introduced
Season
Cool

Areas with shallow water, wet meadows, grasslands, and along stream banks.

Plant Community
Riparian
Grasslands
Low elevation
3850
High elevation
7290

General Description

Redtop can be distinguished from other bent grasses by its colorful purplish-red seedhead. Other bent grasses have a seedhead that is green or gray and their leaf blades are narrower.

Rhizomes; seedhead stem 8 to 47 inches tall; seedhead 3 to 11 inches long, less than 1/2 the length of the seedhead stem, open at flowering otherwise contracted. One-flowered spikelets. Ligules of the upper leaves less than 1/4 inch long.

Grass type
Perennial mat or sod-forming
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 - fingerlike
Seedhead droops
No
First bloom month
March
Last bloom month
April

Flower Characteristics

Flowers per Spikelet
One-flowered
Spikelets One-Sided
No
Awns
Absent
Three Awns
No
Awns bent
No
Flower and Seedhead Notes

Loose panicles, taller than wide, 3 to 11 inches long, egg-shaped to pyramidal. Spikelets are typically purplish red, somewhat flattened, lance-shaped tapering to a pointed tip, with a single floret and a short, straight, rough-textured stalk.

Vegetative Characteristics

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

Leaves are alternate, 2 to 8 inches long, up to 1/3 inch wide, flat, hairless and mostly smooth on both surfaces.

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

Cattle prefer nearly all other cultivated grasses to redtop. It is commonly used for erosion control in plantings along riparian zones and wetlands.