As currently envisioned, Pennisetum is a genus of 80 to 140 species. The various species are native to Africa, Asia, Australia, and Latin America, with some of them widely naturalized in Europe and North America, as well as on various oceanic islands.
They are annual or perennial grasses. Some are petite while others can produce stems up to 8 meters tall. The inflorescence is a very dense, narrow panicle containing fascicles of spikelets interspersed with bristles. There are three kinds of bristle, and some species have all three, while others do not. Some bristles are coated in hairs, sometimes long, showy, plumelike hairs that inspired the genus name, the Latin penna ("feather") and seta ("bristle").