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. cusickii Vasey

Perennial, ± densely cespitose, 1–6 dm, ± dioecious
Leaf: sheath open 1/5–3/4 length; ligule generally 1–6 mm (on sterile stems < 2 mm, truncate, scabrous); blade longest at mid-stem, on sterile stems generally 0.5–1 mm wide, ± firm, inrolled (sometime also folded), upper surface finely hairy
Inflorescence 2–12 cm, lanceolate to ovate, generally dense; branches ascending to appressed, slender, smooth or scabrous
Spikelet: callus generally glabrous; lemma keeled, generally glabrous (rarely keel sparsely hairy), smooth or scabrous; palea keels scabrous
Flower: fertile anthers 2–3.5 mm
Ecology: Moist to dry meadows, sagebrush scrub, montane forest
Elevation: 1500–3600 m.
Bioregional distribution: Klamath Ranges, High Sierra Nevada, Great Basin Floristic Province
Distribution outside California: to s Canada, ND, Colorado

Native

subsp. epilis (Scribn.) W.A. Weber

SKYLINE BLUEGRASS

Leaves: basal tuft sparse; sheath open 1/3–2/3 length; 1–2 nodes well exposed
Inflorescence 3–6 cm, dense; branches appressed, ± smooth, longest generally 10–22 mm
Spikelet: lemma 4–5.8 mm, glabrous or scabrous
Flower pistillate
Chromosomes: 2n=56
Ecology: Moist subalpine, especially snowbeds
Elevation: 2400–3600 m.
Bioregional distribution: High Sierra Nevada
Distribution outside California: to British Columbia, Montana, Colorado
Synonyms: P. epilis Scribner
Horticultural information: IRR: 1, 2, 3.