General: Red Brome Grass (Bromus rubens) is an exotic species that grows densely under native shrubs and in the open spaces between shrubs. This grass sprouts early in the spring, grows quickly, then sets seed and dies, leaving a dense carpet of dry grass that carries fires in areas that once rarely burned because the shrubs were spread too far apart. Because it burns so easily, Red Brome Grass threatens to change the Mojave Desert from a shrub-dominated landscape to an open grassland. A related grass, Cheat Grass, is having a similar effect on the Great Basin Desert.

Red Brome Grass looks much like any other grass, but it can be recognized because it forms dense carpets of individual plants. The seed heads tend to stand erect (not obviously drooping). This is one of the species that fills your socks with prickly seeds.

Red Brome is a common component of all vegetation associations in the Lower Sonoran (Creosote-Bursage Flats) and Upper Sonoran (Mojave Desert Scrub) life zones.

Family: Grass (Poaceae).

Other Names: bromus, cheat grass; foxtail chess, Bromus madritensis, ripgut grass.

Plant Form: Annual grass. Tuft of leaves at the base with taller flower stalks. Grows in dense carpets of individual plants (not a sod-like species), especially under shrubs.

Height: Usually about 10 inches (4 to 20 inches).

Stems: Round, hollow, covered with minute hairs; nodes swollen.

Leaves: Basal, alternate, 2-ranked, linear; hairy; blade flat to inrolled, 1–4 mm wide

Flowers: Blooms March to June. Inflorescence 3–8 cm, cylindrical, dense, panicle-like, on a stiff stalk. Flowerheads upright (not obviously drooping).

Seeds: Small achene-like grain (like a sunflower seed) in a sheath with a sharp, pointed end and a long (to 1 inch) tail. Sticks in your socks and stabs your ankles.

Habitat: Dry, well-drained sandy, gravelly, and rocky soils on upper bajadas and moderate slopes in the lower mountains.

Elevation: To 7,000 feet.

Distribution: Native to Europe and Eurasia, introduced widely across the western U.S.

Comments: This invasive exotic species is changing the nature of vegetation in the Mojave Desert. Before Red Brome Grass invaded, shrubs were widely spaced across much of the desert. When wildfires started, typically they would burn a few shrubs and burn out because the flames couldn't reach the next shrub. Since the invasion, Red Brome Grass has filled in the spaces between shrubs, allowing fires to spread quickly and widely. After the native species burn, more Red Brome Grass grows in, making it harder for native species to grow back. In addition, Red Brome Grass makes it so that fire can burn every year with the potential to suppress the reestablishment of native species. In the long term, the change in the natural fire cycle has major implications for native shrubs in the Mojave Desert. In the Great Basin Desert, Cheat Grass is similar to Red Brome Grass, with the potential to convert large areas of Sagebrush to annual grasses.