Poaceae
Spikelets unisexual, male and female markedly different and in different inflorescences; plants monoecious or dioecious
Female flowers arranged in a globular head 20–30 cm diam. Plants dioecious. Stoloniferous perennials on coastal sand dunes.
Spikelets bisexual or, if unisexual, then male and female very similar and in the same inflorescence
Rhachis flattened, corky; the spikelets sunken in the rhachis Stenotaphrum