POACEAE

GRASS FAMILY

James P. Smith, Jr., except as specified

Annual to bamboo-like; roots generally fibrous
Stem generally round, hollow; nodes swollen, solid
Leaves alternate, 2-ranked, generally linear; sheath generally open; ligule membranous or hairy, at blade base
Inflorescence various (of generally many spikelets)
Spikelet: glumes generally 2; florets (lemma, palea, flower) 1–many; lemma generally membranous, sometimes glume-like; palea generally ± transparent, ± enclosed by lemma
Flower generally bisexual, minute; stamens generally 3; stigmas generally 2, generally plumose
Fruit: achene-like grain
Genera in family: 650–900 genera; ± 10,000 species: worldwide; greatest economic importance of any family (wheat, rice, maize, millet, sorghum, sugar cane, forage crops, ornamental, weeds; thatching, weaving, building materials)
Reference: [Hitchcock 1951 Manual grasses US, USDA Misc Publ 200; Clayton & Renvoise 1986 Kew Bull Add Series 13]
See Glossary p. 26 for illustrations of general family characteristics. Generally wind-pollinated.

ELYMUS

Mary E. Barkworth

Perennial, sometimes from rhizomes
Stem generally bent at base or erect, generally tufted
Leaf: sheath appendaged, appendages sometimes small, fragile; ligule membranous, truncate to obtuse; blades flat, folded, or rolled
Inflorescence spike-like, open to dense; axis generally not breaking apart in fruit; spikelets ± 2-ranked or not, 1–4 per node, generally ascending
Spikelet: glumes lanceolate to awl-like, sometimes 0, awned from tip or not; florets 1–7; lemma generally > glumes, generally rounded, tip acute to awned, awn straight or curved outward; anthers 1–6 mm
Species in genus: 150 species: temp worldwide
Etymology: (Greek: ancient name for millet)
Reference: [Barkworth & Dewey 1985 Amer J Bot 72:767–776; Wilson 1963 Brittonia 15:303–323]
See Agropyron, Elytrigia, Leymus, Pseudoroegneria for species sometimes treated here. Some species hybridize; hybrids with Hordeum, Leymus, Pseudoroegneria also occur.