Bromus tectorum L.
( Cheatgrass )Cheatgrass, also known as Drooping Brome, is an annual grass which germinates in the fall or early spring. A mature plant can grow to between 1 inch and 2 feet high. Cheatgrass is an aggressive and invasive grass that originated in grassland steppe of Eurasia. It was introduced to North America in the late 1800s thru contaminated seeds, in the ballasts of ships, and even on purpose in an ill-advised university experiment. Now cheatgrass can be found in all 50 states, including Alaska and Hawaii. It is most prevalent in the Columbia Basin and in our own Great Basin.
Cheatgrass is highly adaptive and easily grows in all kinds of soils except for those which are very wet or very alkaline. The plant is found moslty in the 150-560 mm precipitation zone. It can be found everywhere from desert valleys to high mountain peaks. It's altitude growth range is between 2,500 and 13,000 ft.
The name, Cheatgrass, Bromus tectorum's most common name, probably comes from observation of the plants life cycle. Cheatgrass' success lies in its annual life cycle as compared to the perennial life cycle of native grasses and shrubs. Cheatgrass germinates, lays seed, and dies every year. During the winter and early spring, when most native plants are dormant, Cheatgrass seeds are germinating. By early spring, the new seedlings are sucking the moisture out of the soil. This is helped by the fact that Cheatgrass seedlings quickly produce very large root structures in the spring that extend deep into the soil. As native perennial grasses (still alive from the season before) come out of their winter dormancy, they need high moisture levels in the soil to grow and produce seeds. By now, however, the Cheatgrass has used up much of the water in the soil. This retards the growth and reproduction of the native plants, thus "cheating" them of continued success.
Perhaps Cheatgrass' most successful adaptation is its relationship with fire. By late spring, it has already deposited its seeds and by early summer, the adult plant dies. The plant then dries out completely and becomes very flammable. As the hapless native shrubs and grasses press on into the hot summer months trying to grow and make seed, they find themselves surrounded on all sides by dead, tinder-dry Cheatgrass just waiting for that strike of lightning or tossed cigarette to let loose its biggest weapon, fire. Where normally there would be little fuel for fire, with Cheatgrass present there is an abundance of fuel. With wind, Cheatgrass fires can rage up to 8 ft high and can move at 4½ mph. These fires are hot enough to ignite the larger shrubs, killing them off. The frequency of fires increases. Before cheatgrass invasion, fires burned once every 60 to 110 years, but after invasion, on average, fires burn every three to five years.
