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©Copyright 1993 by the Regents of the University of California
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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.


J. Travis Columbus

Perennial, cespitose, rhizomed
Stem ascending to erect, solid; nodes generally hairy
Leaf: ligule membranous, ciliate-fringed; blade firm, flat to inrolled, sharply acute
Inflorescence spike-like, generally cylindric; spikelets in clusters ± equal, 3 per node; clusters wedge-shaped, overlapping, appressed to ascending, hairy-tufted at base, falling as 1 unit; axis wavy; glumes of cluster together involucre-like
Central spikelet subsessile, appressed to or nearest inflorescence axis; glumes equal, < floret, oblanceolate, keeled, ciliate, tip deeply 2-lobed, lobes lanceolate, awns 3–9, 1 from ± mid-keel, others terminal; florets generally 1–2, lower floret bisexual, upper floret (if present) bisexual or staminate; lemma lanceolate, 3-veined, generally ciliate, tip generally 2-lobed, generally 1-awned ± from sinus; palea ± = lemma
Lateral spikelets sessile; glumes < to ± = florets, ciliate, lower glume asymmetric with 1 awn from ± middle near margin, generally 2-lobed, lobes unequal; florets 1–4, generally staminate; lemma 3-veined, tip generally ciliate; palea ± = lemma
Species in genus: 3 species: w US, n Mex
Etymology: (Greek: side needle, from awn position on lower glume of lateral spikelets)
Reference: [Reeder & Reeder 1988 Madroño 35:6–9]


P. rigida Thurb.


Plant 3.5–10 dm, branched above base, generally bush-like
Stem 1.5–3.5 mm diam at base; internodes sparsely to densely curly-hairy; node hairs curly
Leaves generally cauline, generally sparsely to densely curly-hairy, especially near and sometimes overlapping ligule; ligule membrane < 1 mm, appendages 0; blade < 10 cm, 2–4 mm wide
Inflorescence 4–10 cm; spikelet clusters 7–11 mm
Central spikelet: glume margin hairs 0.5–3 mm; lower lemma tip sometimes 4-lobed, awns 3 ± from sinuses, central awn 2–5.5 mm
Lateral spikelets: lower glume with 1+ subsidiary lobes, or larger lobe tip fringed, awns 2–4; upper glume tip with 2+ lobes or fringed, awns 1–3, 0.4–2.5 mm, margin hairs 0.5–2 mm; lemma tip 2-lobed, awn 1 ± from sinus, 0.4–2 mm, margin hairs 0.2–1 mm
Chromosomes: 2n=18,36,±108
Ecology: Common. Dry, open, sandy to rocky slopes, flats, and washes, sand dunes, scrub, woodland
Elevation: < 1600 m.
Bioregional distribution: Peninsular Ranges, e&s Mojave Desert, Sonoran Desert
Distribution outside California: to Utah, n Mexico
Flowering time: Feb–Jun
Synonyms: Hilaria r. (Thurber) Scribner
Important forage; some plants from e DMoj and Ord Mtn (San Bernardino Co.), with ± straight internode hairs, intermediate to P. jamesii
Horticultural information: SUN, DRN: 2, 3, 7, 8, 9, 10, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 &IRR: 11, 12, 13; also STBL.

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