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.

TRISETUM

Dieter H. Wilken

Annual, perennial herb
Stems ascending to erect
Leaves basal and cauline; ligule membranous, obtuse to truncate, toothed, tip ciliate or not; blade flat to inrolled
Inflorescence panicle- to spike-like, open to compact, cylindric to narrowly conic
Spikelet: glumes ± unequal, generally = or < lower floret, keeled, acute, lower 1-veined, upper 3-veined; axis stiff- to soft-hairy, generally prolonged behind upper floret, bristly or with vestigial floret; florets 2–3, bisexual, breaking above glumes and between florets (sometimes below glumes); callus short-hairy; lemmas ± keeled, tip 2-bristled or not, awned on back near tip or not, awn straight to bent; palea = or < lemma
Species in genus: 50–70 species: temp, tropical mtns
Etymology: (Latin: three bristle)
Some species intergrade; needs critical study in w North America.

Native

T. spicatum (L.) K. Richt.

Perennial, cespitose
Stems 0.5–4 dm, densely clumped
Leaves mostly basal, tufted; ligule 1–3 mm; cauline blade generally 1–4 mm wide
Inflorescence spike-like, 2–8(10) cm, dense, cylindric to narrowly elliptic in outline; lower branches erect, ± appressed; axis hairy, hidden by spikelets
Spikelets on branches from base to tip; glumes lanceolate, acute, lower 5–6 mm, upper 6–7 mm; lemmas 4–5 mm, awn 4–8 mm
Chromosomes: 2n=14,28,42
Ecology: Open, dry to moist sites, meadows, streambanks
Elevation: 1400–4000 m (KR: 150–2000 m).
Bioregional distribution: Klamath Ranges, High Cascade Range, Sierra Nevada, n East of Sierra Nevada, White and Inyo Mountains
Distribution outside California: temperate America, Eurasia
Flowering time: Jul–Aug
Horticultural information: DRN, SUN: 4, 5, 6 &IRR: 1, 2, 7, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24.