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. piperi Hitchc.

PIPER'S BLUEGRASS

Perennial from rhizomes, tufted, 2–5.5 dm, dioecious
Leaf: sheath open 1/3–2/3 length; ligule 1–2 mm, scabrous; blade 1.5–3 mm wide, firm, folded, inrolled, collar and upper surface of sterile stem blades finely hairy
Inflorescence generally 4–8 cm, sparse; branches ascending
Spikelets few; callus diffusely cobwebby; lemma 4–7 mm, glabrous, smooth to scabrous
Flower: fertile anthers 2–3 mm
Chromosomes: 2n=28
Ecology: UNCOMMON. Serpentine, talus, chaparral, forest openings
Elevation: 100–500 m.
Bioregional distribution: nw Klamath Ranges (Del Norte Co.)
Distribution outside California: sw Oregon
Sometimes mistaken for P. rhizomata Hitchc
Horticultural information: DRY: 5, 17.