Medusahead-rye

Taeniatherum caput-medusae, commonly called medusahead, is an annual grass of the family Poaceae native to southern Europe, North Africa, and southwestern to central Asia, and a highly aggressive invasive in the rangelands of the western United States and elsewhere. It produces erect to slightly geniculate, slender culms 15–60 cm tall, usually tufted from a small fibrous root system. The leaf blades are narrow, 2–10 cm long and 1–3 mm wide, flat to involute, sparsely hairy, with a short, membranous, ciliate ligule. The inflorescence is a dense, stiff, distichous spike 1.5–4 cm long (excluding awns) that bears two-flowered spikelets along the rachis. From each spikelet two stiff, antrorsely barbed, spreading awns 3–10 cm long emerge in a tangled, serpentine mass that gives the species its evocative scientific and common name. The high silica content of the spike makes the dry residue resistant to decay and unpalatable to livestock, leading to thick mats that suppress native vegetation. The species favours clay soils on warm, semi-arid slopes.