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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. palustris L.

FOWL BLUEGRASS

Perennial, cespitose or with stolons, generally 2.5–12 dm
Leaf: sheath open 3/4 length to near base; ligule 1–3 mm, acute to rounded; blade 1.5–6 mm wide, soft, generally flat, often > sheath, slenderly prow-tipped, base closely ascending
Inflorescence generally 10–30 cm, eventually open, lanceolate to narrowly triangular, many-flowered; branches ascending to spreading in fruit, scabrous on angles
Spikelet: lower glume generally 3-nerved; callus cobwebby; lemma generally 2–3 mm, keel and marginal veins hairy
Flower: anthers 0.8–1.4 mm
Chromosomes: 2n=28
Ecology: Disturbed ground in moist forests or sagebrush scrub, meadows, along streams
Elevation: 1500–2000 m.
Bioregional distribution: Northwestern California, High Cascade Range, San Gabriel Mountains, San Bernardino Mountains, East of Sierra Nevada
Distribution outside California: cool temperate; native to Europe
Flowering time: Spring–early summer

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