Jepson Flora Project: Jepson Interchange    

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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California

  • Up-to-date information about California vascular plants is available from the Jepson eFlora.



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.



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.


P. secunda J. Presl

Perennial, densely cespitose, 1.5–10 dm
Leaf: sheath open 3/4 length to near base; ligule 0.5–10 mm, truncate to acuminate, sometimes scabrous; blade generally 0.5–3 mm wide, soft to firm, flat to folded or inrolled
Inflorescence 2–25 cm, often ± 1-sided, generally linear to lanceolate, generally dense; branches generally appressed to ascending (generally spreading only in flower), ± scabrous
Spikelet ± cylindric or little compressed; upper internodes generally > 1.2 mm; callus glabrous or with a ring of short hairs; lemma 3.5–5 mm, weakly keeled to rounded across lower back, glabrous to ± evenly short-hairy across body (rarely soft-hairy only on veins), smooth to scabrous
Flower: anther 1.5–3 mm
Chromosomes: 2n=42–106 (mostly high polyploids)
Ecology: Common. Many habitats
Elevation: 0–3800 m.
Bioregional distribution: California
Distribution outside California: to Alaska, Rocky Mtns, nw Mexico, also in S.America
Many ecological forms; subspp. tend to intergrade.


subsp. juncifolia (Scribn.) Soreng

Plant 3–12 dm
Leaf: ligule 0.5–6 mm, truncate to acuminate, scabrous (those on lateral shoots 0.5–2 mm); blade generally < 1.5 mm wide, ± firm, tightly folded and inrolled, retaining shape, often glaucous
Inflorescence generally 6–25 cm
Spikelet: lemma 3.5–6 mm, glabrous (rarely sparsely short-hairy on keel and marginal veins near base); palea keels scabrous
Chromosomes: 2n=±63 most often
Ecology: Sagebrush scrub to lower montane forest, often in alkaline depressions
Elevation: 900–3000 m.
Bioregional distribution: High Cascade Range, High Sierra Nevada (especially e slope), Great Basin Floristic Province
Distribution outside California: to s Canada, ND, New Mexico
Flowering time: Early Summer
Several important ecotypes: 1) " P. ampla Merr." (big bluegrass: plant 6–12 dm; leaf blade flat, generally glaucous; non-alkaline); 2) " P. juncifolia Scribner" (alkali bluegrass: leaf blade folded and inrolled, ligule truncate; often alkaline); 3) " P. nevadensis Scribner" (Nevada bluegrass: leaf blade folded and inrolled, ligule long, acute; often alkaline). " P. pratensis X P. secunda " [P. fibrata Scribner; P. X limosa Scribner & Williams (Lassen Co. bluegrass, see key: 16.) is a set of hybrids between P. s. subsp. j. and P. pratensis; 2n=63–64; low, often saline meadows; 800–2000 m; range of subsp. j.
Horticultural information: DRY: 1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24; salt tolerant.

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