AppearanceBromus arvensis is an annual in the grass family (Poaceae). It is a cool season, annual grass that can range in height from 14-40 in. Foliage Leaf blades are flat, covered with soft, distinct, thin hair, approximately 1-8 in. in length, and 1/32-1/16 of an in. wide. Sheaths are covered with dense, soft hairs. Ligules are 1/64-1/16 of an in. long and auricles are absent. Flowers Inflorescence is an open panicle, 2-7 in. long with spreading, usually drooping branches. Spikelets are 6 to 10 flowered, 1/2-1 in. in length, and 1/8-1/4 of an inch wide. First glumes are usually 3- to 5- nerved, 1/8-1/4 of an inch long. Second glumes are 5- to 9-nerved and 1/4-1/2 of an inch in length.Fruit Lemmas are broader at the upper-half, tapering to the bottom, with margins not strongly enrolled in the fruit. Awns are 1/4-3/4 in. long, somewhat twisted and widely spread at maturity. Ecological ThreatBromus arvensis can be found on a wide variety of soils that include sand, silt, and clay, but thrives on fine-textured soils. Waste areas, disturbed sites, roadsides, pastures, rangelands, and wheat fields are areas where Bromus arvensis can establish. The plant is a common component of many mixed prairie communities. It is an aggressive species that out-competes desirable vegetation for water and soil nutrients, thus reducing plant biodiversity. Forage production of perennial grasses and grazing performance is also reduced in areas infested with Bromus arvensis.