Plant Story--Cheatgrass, Downy Brome, Bromus tectorum, Dreadful Weed

 Cheatgrass, also known as downy brome and downy chess, Bromus tectorum (grass family Poaceae) is a very small grass that has become a major weed. Generally we think of problems increasing as plants get bigger. Individual plants of cheatgrass are almost too small to notice. It makes up for that in numbers.

patch of cheatgrass along a trail (red)

Cheatgrass is a winter annual native to southern Europe, nearby southwestern Asia, and north Africa. It spread with humans all over that region long ago. A weed of agricultural fields and crop plants, it likely first came to the North America in contaminated ballast of ships but arrived many times. It was collected in Pennsylvania in 1790 (specimen has been lost, so identification can't be verified), in St. Louis about 1850 and in British Columbia in 1890. Those were likely all new arrivals from overseas; the St. Louis report is from the port.  It can be found across all of Eurasia and north Africa, and as an invader in South Africa. Likewise, it has spread across Chile, Argentina, Australia and New Zealand. 

Within continents, it spread in contaminated feed, mixed with grain seeds (the seeds are hard to separate from wheat), on domestic animals, and with straw in packing materials. By the 1900s cheatgrass was all across North America and in mid-century people described it as integrated into local ecosystems. It is currently found in all the states of the United States and the provinces of Canada except in the high Arctic. It does not appear on many noxious species lists because those lists are intended to try to eradicate weeds and cheatgrass is so abundant that is not a possibility. There is lots of information on it as a troublesome and difficult weed and advice about controlling it, however. 

Bromus is a grass genus of 100 to 400 species (grass family Poaceae), native to Eurasia and to North America. Bromus is from the Greek bromos, "oats", although oats are not in the genus Bromus. The species epithet, tectorum, is Latin for "of roofs." This little plant frequently grew on the thatched and sod roofs of Europe in Linnaeus's time (mid 1700s). The common name cheatgrass is variously said to be from farmers feeling cheated of good yields of wheat by this weed, or because unscrupulous grain merchants extended the wheat seeds by adding, or not removing, cheatgrass seeds. Either way, farmers and ranchers identified this unfamiliar, invasive species a "cheatgrass." Downy brome and downy chess refer to the fine soft hairs along the stems and leaves of cheatgrass, while brome and chess refer it to other grasses (chess is an old English name for other species now classified as Bromus, but the origins of the name chess for a grass are not understood). 

Cheatgrass seeds are very like wheat and rye seeds in shape, weight, and color, especially when seen in a bag intended for planting. As a result, some American and Canadian farmers concluded that wheat and winter rye seeds could turn into cheatgrass in their fields. 

The seeds generally germinate in the winter and grow whenever the weather is mild or, less often, germinate in the spring. They form dense stands (see photo below) which start their main spurt of growth early in the spring when other plants are just germinating. They can provide good early season grazing for livestock. However, in dry climates like the American West, the early growth of cheatgrass removes much of the water and lots of the nutrients from the soil, so that other plants, growing a little later, struggle. 

cheatgrass, Bromus tectorum, seedlings

Cheatgrass grows quickly to 4-24" tall and start to flower in 6-8 weeks. They can be wind-pollinated but mostly they  self-pollinate. Plants in a dense stand will each produce only a few (about 25) seeds but collectively they produce some 7 million seeds per acre. A plant by itself on a good site can mature 5,000 seeds in its short lifetime. Below, they are the pretty nodding green capsules, full of seeds in late spring. 

Lots of small cheatgrass plants

The growing season is only just well underway when the cheatgrass plants mature their seeds, dry out and die. They turn a pretty red-brown (see first picture and ones below).

cheatgrass (Bromus tectorum) in seed

By this point they are not very edible. The seeds and awns are stiff and can cause injury to the mouths and stomachs of animals. Aldo Leopold pointed out the cheatgrass invasion in the 1940s, writing a memorable essay Cheat Takes Over with observations such as "To appreciate the predicament of a cow trying to eat mature cheat, try walking through it in low shoes. All field workers in cheat country wear high boots." (link). I can attest that they lodge painfully into hiking shoes and socks. 

Cheatgrass plants dry out further, flatten, and scatter seeds. This is the form they are in from mid-summer until the seeds germinate in the fall. As you would expect, dead cheatgrass will easily carry a grass fire in late summer. They are responsible for an increased frequency of fires in western grasslands, especially in the Great Basin (Nevada, much of Utah and surrounding states), endangering people and property and killing native plants. It becomes a vicious cycle: cheatgrass burns, other plants are killed and space on the ground opens up. With rain in fall, cheatgrass seeds germinate, some of their very large number having escaped the fire. These plants dry out in late summer, support another fire which damages more natives and more cheatgrass germinates...

dry, dead cheatgrass

Cheatgrass is hard to control, partly because it grows so fast and so low to the ground, partly because there is so much of it. Control methods that work for a home garden become prohibitive on the scale of the rangelands of the West. And that is where cheatgrass can be found as a common plant, in more than 50 million acres of rangeland. 

Small cheatgrass patch (redbrown among the greens):

Area where cheatgrass is pretty much the only plant

a lot of cheatgrass

Lots of places around the world, this plant is present but not much of a problem. It is part of the pasture grasses in the U.S. South and acceptable fodder. New Englanders can just weed it out of flowerbeds.  As an annual, it has weak roots and is easy to pull up. So, in many places, it is just a cute little Eurasian grass. It is in the U.S. West that this plant forms broad monocultures, enhances fires, and threatens the native species. 

Cheatgrass amid sagebrush in Wyoming 

We don't use cheatgrass except as forage for animals but there are possibilities. You can make flour from cheatgrass seeds, although they are small and difficult to gather (link). The Cahuilla in southern California and sometimes settlers ate the seeds, cooked into a gruel, during famines. The seeds can be roasted into a coffee substitute. The Paiute used it as bedding when camping. 

This is a very common plant, growing all around the world, but, because of it is so small--a couple of stalks less than a foot tall--it is easily ignored. Until it forms extensive reddish stands. As an invasive species, it is a great success story. But it really is invasive, aggressive, and destructive; less of it would be better. 

Comments and corrections welcomed. 

References

This is a much-studied plant, I picked facts out of various long articles. 

Beck. G. K. no date given (citations suggest 2006). Downy brome (Bromus tectorum) and Japanese brome (Bromus japonicus) biology, ecology and management. Literature Review. Washington State Noxious Weed Board. link 

Cheatgrass. Bromus tectorum. Montana Field Guides. Montana National Heritage Program. link (accessed Jan. 19, 2026).

Fernald, M.L. 1970. Gray's Manual of Botany. 8th edition. D. Van Nostrand Company, New York. (explanation of tectorum)

Leopold, A. 1949. Cheat Takes Over. Sand County Almanac and Sketches Here and There. online at The Ted K Archive link (Accessed 1/125/26)

Mack, R. N. and D. A. Pyke. 1983. Demography of Bromus tectorum: variation in time and space. Journal of Ecology. 71: 69-93. 

Martin, A. C. 1972. Weeds. Golden Press, New York.

Moerman, D. E. Native American Ethnobotany. BRIT press. Online data base  (link). (Accessed 1/11/26)

Molvar, E. M., R. Rosentreter, D. Mansfield and G. M. Anderson. 2024. Cheatgrass invasions: History, causes, consequences, and solutions. Western Watersheds Project. link Long, detailed, excellent.

Novak, S. J. and R. N. Mack. 2001. Tracting plant introduction and spread: genetic evidence from Bromus tectorum (cheatgrass). BioScience. 51 (2): 114-122.

Oxford English Dictionary. "chess" "cheatgrass" Oxford English Dictionary Online (accessed 1/10/26). 

Plants for a Future. 2026. Bromus tectorum Plant For a Future website. link

Staver, C. 2024. Introduced Species Summary Project: Cheatgrass (Bromus tectorum) link

Stearn, W.T. 1996. Stearn's Dictionary of Plant Names for Gardeners. Cassell Publishing, London.

Comments and corrections welcome.

Kathy Keeler, A Wandering Botanist
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