34. Bromus L. (brome, brome grass)
Plants with C3 photosynthesis, annual or
perennial. Leaf sheaths closed to well above the middle, sometimes to the tip
or nearly so, the ligules membranous. Inflorescences panicles or less commonly
racemes. Spikelets stalked, slightly to strongly compressed laterally, with
4–30 fertile florets and usually 2 or 3 sterile florets at the tip,
disarticulating above the glumes and between the florets, the rachilla
noticeably zigzag. Glumes 2, usually unequal in length, herbaceous to papery,
1–9‑nerved, usually awnless. Lemmas herbaceous to papery, rounded to
strongly keeled on the back, 5–13‑nerved, the tip divided into two,
minute teeth, with the awn (if present) attached between the teeth. Paleas 2‑nerved,
lacking awns. Stamens (1–)3, the anthers mostly orange. Fruits somewhat
flattened, usually with a longitudinal groove on 1 side. About 150 species,
North America, South America, Europe, Asia, Africa; mostly in temperate
The few species of Bromus native to Missouri are
perennial, clump‑forming species of mesic upland and bottomland forests.
Most species of bromes in the state were introduced for cultivation as pasture
grasses and other fodder (secondarily for erosion control). It is ironic that
in some parts of the country large acreages of native grasses were replaced by
species of Bromus. Although some species are excellent forage grasses,
others are relatively unpalatable to livestock and became known as cheatgrass.
Several species with long awns can even cause injury to the noses, eyes,
mouths, and intestines of cattle and other species that attempt to graze on them.
Following the widespread cultivation of bromes in temperate North America,
various taxa proved weedy and invasive, particularly in disturbed habitats. As
a result, some species are quite widespread and common in Missouri, sometimes
at the expense of native vegetation.