Caucasian bluestem is a perennial, clump-forming, small, graceful, blue-gray grass, with flowering stems to 3 feet tall. It forms dense tufts of smooth, blue-green leaf blades, to 12 inches long and less than ¼ inch wide with a thickened midvein. The nodes are purple-tinged and may be smooth or with short hairs. It blooms far earlier than our native bluestems. The inflorescence is silvery and reddish purple, with side branches that are shorter than the central stem (resembling a miniature version of Johnson grass, which blooms at the same time). Blooms late June through July.
Similar species: The similarly invasive yellow bluestem (Bothriochloa ischaemum) is larger and has yellow-green leaves that are usually smooth; the leaf sheaths are rounded and leaf blades flat or folded; nodes are either smooth or with short hairs. Although its inflorescence is similar to Caucasian bluestem, the length of the side branches exceeds the length of the central stem.
Height: 1 to 3 feet.
Scattered statewide. Has currently escaped cultivation in at least eight counties.
Habitat and Conservation
Old world bluestems (both Caucasian and yellow species) can be found near disturbed roadsides, in pastures, and even in high-quality prairie and glade habitats. They are very difficult to eradicate once established.
Invasive. Caucasian bluestem is a warm-season perennial grass native to subtropical Asia and Africa. It and yellow bluestem were brought to the United States in the early 1900s for use as forage grass and to control erosion. Unfortunately, that effort to “improve” rangeland backfired. These grasses are less palatable and less nutritious to cattle than our native warm-season grasses, and once established, the invasive species are almost impossible to eradicate.
Caucasian bluestem spreads by root and seed. Because foragers and grazers prefer native grasses, the invasive Old World bluestems have a competitive advantage. These aggressive weeds can also cause an altered carbon-to-nitrogen ratio in the soil that inhibits the growth of native plants.
Despite their inferiority as fodder, invasive nature, and negative effect on cultivated and natural lands, these grasses are still sometimes recommended by unprincipled seed-sellers, and some Missouri cattle ranchers cultivate them because they can withstand close grazing. Their use for erosion control is highly discouraged.
Invasive bluestems alter soil chemistry and biota, suppressing the growth of native grasses. The sod they form is unsuitable for quail nesting or cover. They aggressively outcompete native plants and, once established, are almost impossible to eradicate.