Aristida and Stipa are large and widely distributed genera, occurring especially on open plains and steppes; the conspicuously awned persistent flowering glume forms an efficient means of dispersing the grain.
Each spikelet contains a solitary flower with two outer small barren glumes, above which is a large tough, compressed, often awned, flowering glume, which partly encloses the somewhat similar pale.
In the hard wheats the outer glumes are keeled, sharply pointed, awned, and the seed is elongated and of hard glassy texture, somewhat translucent, and difficult to FIG.
The species of Heteropogon, a cosmopolitan genus in the warmer parts of the world, have strongly awned spikelets.