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Agrostis exarata

Agrostis exarata Trin.

Spike Bentgrass, Spiked Bent, Spike Red Top

Poaceae (Grass Family)

Synonym(s): Agrostis aenea, Agrostis alaskana, Agrostis ampla, Agrostis asperifolia, Agrostis exarata ssp. minor, Agrostis exarata var. minor, Agrostis exarata var. monolepis, Agrostis exarata var. pacifica, Agrostis exarata var. purpurascens, Agrostis longiligula, Agrostis longiligula var. australis, Agrostis melaleuca, Agrostis microphylla var. major


USDA Native Status: L48 (N), AK (N), CAN (N)

A tufted grass from 1-4 ft. tall. Culms may be slender to relatively stout and are topped with a seedhead that is usually dense and spikelike but sometimes interrupted and somewhat open. The branches are always strongly erect and green to purplish.


From the Image Gallery

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Plant Characteristics

Duration: Perennial
Habit: Grass/Grass-like
Root Type: Fibrous
Leaf Arrangement: Alternate
Leaf Complexity: Simple
Leaf Venation: Parallel
Fruit Type: Caryopsis
Size Notes: Up to about 4 feet tall, often shorter.
Leaf: Green

Bloom Information

Bloom Color: Yellow , Green , Brown
Bloom Time: Apr , May , Jun , Jul , Aug , Sep , Oct


USA: AK , AZ , CA , CO , ID , KY , MT , NE , NM , NV , OK , OR , SD , TX , UT , VT , WA , WY
Canada: AB , BC , SK
Native Distribution: AK to CA, e. to Alt., TX & Mex.; also locally to the Dakotas & NE
Native Habitat: Moist meadows; canyons

Growing Conditions

Water Use: Medium
Light Requirement: Part Shade
Soil Moisture: Moist
CaCO3 Tolerance: Low
Soil Description: Various moist soils.


Use Food: Seeds harvested for food by indigenous peoples.
Attracts: Butterflies
Larval Host: The Grass Family is an essential larval food for most branded skippers and most of the satyrs.

Find Seed or Plants

Find seed sources for this species at the Native Seed Network.

National Wetland Indicator Status

This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Native Seed Network - Corvallis, OR

Web Reference

Webref 30 - Calflora (2018) Calflora
Webref 38 - Flora of North America (2019) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter

Additional resources

USDA: Find Agrostis exarata in USDA Plants
FNA: Find Agrostis exarata in the Flora of North America (if available)
Google: Search Google for Agrostis exarata


Record Modified: 2022-10-31
Research By: TWC Staff

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