Cheatgrass (Bromus tectorum) is an invasive annual grass that has become widespread across North America, particularly in the western states. This plant completes its lifecycle quickly, often outcompeting native vegetation in rangelands and natural areas. Learning to identify cheatgrass by its distinct physical characteristics is a necessary first step in managing its spread.
General Appearance and Vegetative Features
When cheatgrass first emerges in the late fall or early spring, it appears as a bright, light green grass growing in small, erect bunches. The plant typically reaches a height of 6 to 24 inches. Its stems are slender and generally grow upward from a single base, sometimes giving the plant a tufted appearance.
A hallmark of cheatgrass identification is the texture of its leaves and sheaths. These structures are conspicuously covered in soft, fine hairs, giving the entire plant a downy or fuzzy feel. The leaves themselves are relatively narrow, usually less than a quarter-inch wide, and may sometimes exhibit a slight spiral twist, especially when the plant is young. This dense hairiness is the feature that gives the plant its alternative common name, downy brome.
Distinctive Seed Head and Awn Characteristics
As the plant matures, the reproductive structures, or seed heads, become the most definitive visual marker. Cheatgrass produces a loose, open grouping of spikelets called a panicle, which characteristically hangs or nods to one side of the stem.
Each individual spikelet within the panicle contains several florets. Extending from these seed casings are long, stiff bristles known as awns, which are a major feature for positive identification. These awns are notably long, often measuring between 3/8 to 3/4 of an inch, and are straight or slightly twisted. The awns are sharp and sometimes barbed, enabling the seeds to easily catch onto clothing, fur, and animal hides.
Identifying Cheatgrass by Location and Lifecycle
Cheatgrass is a winter annual, meaning its seeds typically germinate in the fall, establish a root system over the winter, and then rapidly grow in the early spring. This early start allows the plant to utilize moisture and nutrients before most native grasses begin their growth cycle. Its quick development means it is often the first grass to turn green in the spring.
The plant’s rapid lifecycle results in an early color change that is highly visible in the landscape. After flowering, the foliage and seed heads transition from green to shades of reddish-purple or reddish-brown as they dry out. Crucially, cheatgrass cures to a pale tan or straw color, often by late spring or early summer, weeks before native perennial grasses have dried. This early drying creates large, distinct patches of light-colored, dry grass. The plant thrives in areas with disturbed soil, making it a common sight along roadsides, in waste areas, and on overgrazed rangelands.