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 not arranged in a globular head
Female flowers not surrounded by a bony utricle. Plants dioecious
Leaves crowded near the base of the plant, at least 1 m long. Inflorescence up to 1 m long, drooping Cortaderia
Leaves distributed along the upright stems. Inflorescence pyramidal, erect