Poaceae

Perianth segments 0–3, usually 2; flowers grouped into a characteristic spikelet (Fig. 48) Poaceae
Spikelets bisexual (rarely unisexual, and if so, the spikelets similar and in the same inflorescence)
Spikelets in pairs (or rarely triplets), usually one sessile and awned, the other pedicellate and awnless (Fig. 50 l). The sessile spikelet can be sunken into the thick rhachis (Fig. 47 h) or; the two spikelets are similar, awnless and surrounded by silky hairs or; the pedicellate spikelet is reduced to the pedicel (Fig. 50 n). Spathe present just below the inflorescence in some genera.
Inflorescence rhachis thickened. Spikelets closely appressed and sometimes embedded in the rhachis (Fig. 47 h)
Inflorescence rhachis not markedly thickened, spikelets not embedded in the rhachis