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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.

ACHNATHERUM

NEEDLEGRASS

Mary E. Barkworth

Perennial, tufted
Stem generally erect
Leaf: ligule membranous, sometimes long-ciliate, blade generally flat
Inflorescence panicle-like, generally narrow; branches generally ascending
Spikelet: glumes > floret (except awn), tapered below midpoint; axis breaking above glumes; floret 1, generally cylindric; callus blunt or sharp, hairs stiff; lemma stiffly membranous to hard, evenly hairy or glabrous above, awned from tip; awn > 10 mm, persistent, with 1–2 bends, or < 10 mm, readily deciduous, ± straight; palea < lemma, hairy, veined
Species in genus: ± 75 species: temp worldwide
Etymology: (Greek: awned scale, from lemma)
Segregated mostly from Stipa ; see also Hesperostipa, Nassella.

Native

A. hymenoides (Roem. & Schult.) Barkworth

INDIAN RICEGRASS


Stem 2.5–7 dm
Leaf: blade rolled, < 1 mm diam
Inflorescence ± open; branches, spikelet stalks widely spreading
Spikelet: glumes 5–9 mm, ± equal, base swollen; floret 3–4.5 mm; callus sharp; lemma ± spheric, hairs 2.5–6 mm, awn 3–6 mm, deciduous
Chromosomes: 2n=46,48
Ecology: Dry, well-drained, often sandy soil, desert scrub, sagebrush scrub, pinyon/juniper
Elevation: < 3400 m.
Bioregional distribution: Cascade Range, Sierra Nevada, w San Joaquin Valley, Southwestern California, Great Basin Floristic Province, Desert
Distribution outside California: to British Columbia, Great Plains, Mexico
Flowering time: Apr–Jul
Synonyms: Oryzopsis h. (Roem. & Schult.) Ricker
Hybrids with other species, including O. X bloomeri (Bol.) Ricker, have narrower florets and awns 12–16 mm. Used by Native Americans for food; highly palatable to livestock
Horticultural information: DRN, DRY, SUN: 1, 2, 3, 7, 8, 9, 10, 11, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24; STBL.

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