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. confinis Vasey

BEACH BLUEGRASS

Perennial from slender rhizomes or stolons, delicate, tufted, 0.7–3 dm, ± dioecious
Leaf: sheath open 1/2–2/3; ligule < 2 mm, obtuse to acute, scabrous; blade 1–2 mm wide, ± firm, folded, inrolled, upper blade surface on sterile stems generally finely hairy
Inflorescence generally 1–5 cm, ovate, ± tawny; branches ± appressed, ± scabrous
Spikelet: callus glabrous or diffusely short-cobwebby; lemma 2–4.5 mm, glabrous or sparsely hairy
Flower: fertile anthers 1.5–2 mm
Chromosomes: 2n=42
Ecology: Ocean beaches, stabilized dunes
Elevation: < 100 m.
Bioregional distribution: North Coast
Distribution outside California: to British Columbia
Fls spring
Horticultural information: DUNE: 5, 17, 24; STBL.