Vegetative key to the families

GRASSES. Herbs. Leaf bases modified to form an open sheath which encloses the stem; leaf blade with parallel venation and abruptly distinct from the sheath; LIGULE usually present at the top of the sheath (Fig 24) 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.
Female flowers not arranged in a globular head