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©Copyright 1993 by the Regents of the University of California

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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.

POA

BLUEGRASS

Robert J. Soreng

Annual, perennial herb, some ± dioecious
Stem 0.3–12 dm
Leaf: sheath open to closed (best observed on upper stem leaf); ligule thin, flexible; blade grooved above on both sides of midvein, flat, folded, or inrolled, generally smooth or scabrous on veins, generally prow-tipped
Inflorescence panicle-like; branches appressed to drooping
Spikelet generally compressed, breaking between florets; glumes 2, similar, generally < lowest lemma, awnless; florets generally 2–6; callus indistinct, often with obvious tuft of long cobwebby hairs; lemma generally keeled to base, of same texture as glumes, awnless, veins generally 5, ± converging near tip; palea well developed, keels generally scabrous; fertile anthers 0.2–4.5 mm; ovary glabrous
Species in genus: ± 500 species: temp and cool regions
Etymology: (Greek: ancient name)
Reference: [Soreng 1991 Syst Bot 16:507–528]
CA is center of diversity in North America. Spikelet features best observed on lowest florets of spikelet.

Introduced

P. trivialis L.

ROUGH BLUEGRASS

Perennial, short-lived, cespitose or with short stolons from a dense basal tuft, 3–10 dm
Leaf: sheath open generally 3/4, scabrous; ligule 3–7 mm, acute, scabrous; blade 1–5 mm wide, soft, generally flat, barely prow-tipped
Inflorescence 8–25 cm, open, lanceolate to ovate; branches ascending to spreading, densely scabrous, many-flowered from lower 1/2
Spikelet: lower glume 1-veined, ± sickle-shaped; callus sparsely long-cobwebby; lemma ± 2–3 mm, keel (rarely marginal veins) hairy near base
Flower: anthers 1.4–2 mm
Chromosomes: 2n=14
Ecology: Disturbed moist places
Elevation: 0–700 m.
Bioregional distribution: North Coast, Outer North Coast Ranges, probably elsewhere
Distribution outside California: to Alaska, e N.America; native to Europe
Fls spring and early summer.

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