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. webberi (Thurb.) Barkworth

Stem 1–3.5 dm
Leaf: blade generally rolled, < 0.5 mm diam, stiff
Inflorescence 2.5–7 cm, dense, often partly enclosed by upper leaf sheath
Spikelets: glumes 6–10 mm, ± equal; floret 4.5–6 mm, callus blunt; lemma evenly, densely long-hairy, hairs 2.5–3.5 mm, awn 5–11 mm, straight, readily deciduous; palea ± = lemma
Chromosomes: 2n=32
Ecology: Dry, open flats, rocky slopes, generally with sagebrush
Elevation: 1500–3000 m.
Bioregional distribution: Sierra Nevada, Modoc Plateau, White and Inyo Mountains
Distribution outside California: to Oregon, Colorado
Flowering time: Jun–Jul
Synonyms: Oryzopsis w. (Thurber) Benth
Horticultural information: DRN, SUN: 1, 2, 3, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24; STBL.