Cheatgrass aka Downy brome

Bromus tectorum

Keys to Identification

  • Has reddish or purple drooping awns
  • One of the first plants to green up in the spring

Family

Poaceae – Grass family

Other Names

Downy chess, downy bromegrass, slender chess, drooping chess, junegrass, and bronco-grass

USDA Code

BRTE

Legal Status

Colorado Noxious Weed List C

Identification

Lifecycle

Winter annual 

Growth form

Grass

Flower

Inflorescence is reddish or purple, drooping to one side of the stem. Florets are sharp and awns are straight

Seeds/Fruit

Seeds fall to the ground soon after flowering.  Barbs allow seeds to attach to fur, clothing and gear

Leaves

Leaves and sheaths are covered in short, soft hairs

Stems

6-18 inches long

Roots

Shallow, densely fibrous root system. Roots grow throughout the winter and readily use soil moisture early in the spring before other plants germinate

Seedling

Slender green leaves.  Emerges in fall and spring.  Often the first plants to green-up.  May have multiple flushes during rainy summers

Similar Species

Exotics

 

Natives

 

Impacts

Agricultural

Invades agricultural fields and range land. Suppressed other grass species and sharp florets harm grazing livestock. Major pest in winter wheat, may reduce yield up to 80 %

Ecological

Degrades native sagebrush and grassland communities, promotes wildfire

Human

May increase the frequency and intensity of fires, often near buildings

Habitat and Distribution

General requirements

Common in arid fire sensitive communities such as scrub, grassland, and some conifer forests

Distribution

Widespread in Colorado and other western states. Originally from Europe

Historical

Likely introduced to the US as a contaminate in crop seed packing material in the late 1800’s and was first found in the US around Denver, Colorado

Biology/Ecology

Life cycle

Germinates in the fall, overwinters, matures and produces seed by May or June

Mode of reproduction

Seed

Seed production

May produce up to 80,000,000 seeds per acre

Seed bank

Most seed germinate in the fall after dispersal. May last 2-4 years in the soil

Dispersal

Dispersed by wind, rodent activity, or by seeds clinging to fur or clothing. Also by equipment, seed and contaminated hay

References

Weed Control in Natural Areas in the Western United States. University of California Weed Research and Information Center. Pg 66-67 USDA. (2020). Downy Brome.

USDA. (2019). Downy Brome. USDA NRCS Plant Guide.

Washington State University – http://smallgrains.wsu.edu/weed-resources/common-weed-list/downy-brome/

Invasive.org – https://www.invasive.org/browse/subinfo.cfm?sub=5214

BugwoodWiki – https://wiki.bugwood.org/Bromus_tectorum

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