A closeup of a Bromus tectorum individual, with a focus on the seeds. Image from USDA.
Bromus tectorum, also known as cheatgrass or drooping brome, is an invasive annual grass originating from Europe and Asia. Cheatgrass was probably introduced to North America via contaminated shipments of grain or soils from Europe in the late 1800s. Cheatgrass can now be found in all fifty of the United States and most Canadian provinces.
A large number of closely spaced cheatgrass plants. Image from the Bureau of Land Management .
Cheatgrass seeds can spread by wind, attaching to fur or clothing, or by caches made by rodents. The disbursed germinate in the fall, flower in spring, and then usually during the summer.
Cheatgrass grows early and abundant in the season, with sometimes over 10,000 plants occupying a square yard. This can choke out the later growing native species, and the dense mass of dead plants can pose a serious fire risk with the onset of summer. Efforts to control the spread of cheatgrass can include controlled fires, mowing, and interseeding with native plants.
A fire in Milford, Utah fueled by dry cheatgrass. Image from KSL.