One-flowered spikelets may fall as a whole (as in the tribes Paniceae and Andrepogoneae), or the axis is jointed above the barren glumes so that only the flowering glume and pale fall with the fruit.
D, Flowering glume or lower palea.
The awn which is frequently borne on the flowering glume is also a very efficient means of distribution, catching into fur of animals or plumage of birds, or as often in Stipa (fig.
I), the flowering glume having its dorsal rib prolonged into an awn (fig.
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.
The flowering glume has generally a more or less boat-shaped form, is of firm consistence, and possesses a well-marked central midrib and frequently several lateral ones.
The awn may be either terminal or may come off from the back of the flowering glume, and Duval Jouve's observations have shown that it represents the blade of the leaf of which the portion of the flowering glume below its origin is the sheath; the twisted part (so often suppressed) corresponds with the petiole, and the portion of the glume extending beyond the origin of the awn (very long in some species, e.g.
The form of the flowering glume is very various, this organ being plastic and extensively modified in different genera.