POACEAE

GRASS FAMILY

Herbs, rarely shrubs or trees, usually with hollow stems (culms) solid at the nodes, and with 2-ranked, parallel-veined lvs. consisting of 2 parts; the sheath and the blade, the former enveloping the culm with the margins overlapping or rarely grown together. At the junction of the sheath and blade, on the inside, is a membranous hyaline or hairy appendage, the ligule. The flowers are perfect, sometimes unisexual, minute, without a distinct perianth, arranged in spikelets consisting of a shortened axis, the rachilla, and 2-many distichous bracts, the 2 lowest, glumes, being empty; rarely 1 or both of them obsolete; in the axil of each succeeding bract, the lemma, is borne a single floret, subtended and usually enveloped by a 1-2 nerved bract, the palea, with its back to the rachilla; at the base of the flower between it and the lemma, are usually 2 very small hyaline scales, lodicules. Stamens usually 3, with delicate fils. and 2-celled versatile anthers. Pistil 1, with a 1-seeded, 1-ovuled ovary, usually 2 styles and plumose stigmas. Fruit a caryopsis with starchy endosperm and usually enclosed at maturity in the lemma and palea, free or adnate to the latter. The lemma with its palea and flower constitute a floret. Spikelets arranged in spikes, racemes or panicles with bractless branches. About 600 genera and 7500 spp.; from all parts of the world. (Munz, Flora So. Calif. 934).