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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.

Native

P. howellii Vasey & Scribn.

Annual, cespitose, 3–8 dm
Leaf: sheath open 1/8–1/2 length; ligule 2.5–5 mm, truncate to acute; blade generally 1–6 mm wide, soft, generally flat, barely prow-tipped
Inflorescence generally 20–25 cm; branches ascending in flower, spreading to reflexed in fruit, with spikelets only in top 1/2, densely scabrous
Spikelet: internodes generally < 1 mm, some hairy; callus cobwebby; lemma ± 3 mm, short-hairy over body; palea keels scabrous or short-hairy
Flower: anthers 0.2–1 mm
Ecology: Rocky banks, shaded slopes of woodlands, chaparral, disturbed places
Elevation: generally < 1000 m.
Bioregional distribution: California Floristic Province
Distribution outside California: to British Columbia
Synonyms: P. bolanderi subsp. h. (Vasey & Scribner) D.D. Keck
Fls spring.

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