any of about 20 species of grasses constituting the genus Erianthus (family Poaceae), native to warm regions of the Northern and Southern hemispheres. Plume grasses are tall, reedlike perennials with dense, cylindrical, plumelike panicles. Most species are 1 to 3 m (3 to 10 feet) tall, but Ravenna grass (E. ravennae), native to southern Europe, grows to 4 m (13 feet). It is cultivated as an ornamental for its long (0.6 m 【2 feet】) panicle.