The rachis is the main axis of the inflorescence, or spike, of wheat and other cereals, to which the spikelets are attached. Spikelets are small inflorescences bearing one or more florets, or small flowers, along with a set of miniature bractlike leaves. When the fruits of the wild-type wheat are fully ripened, a series of abscission layers forms that divides the rachis into dispersal units consisting of a single spikelet attached to a short segment of the rachis. A ripe head of wheat is thus easily shattered into dispersal units when touched or blown by the wind. This is refered to by archaeologists as a "brittle rachis".