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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.

HESPEROSTIPA

Mary E. Barkworth

Perennial, cespitose
Stem erect, unbranched
Leaf: blade upper surface conspicuously ridged, generally inrolled
Inflorescence panicle-like, narrow
Spikelet: glumes tapered from near base to acute tip, awn 0; axis breaking above glumes; floret 1, 7–25 mm, narrowly cylindric; callus 2–5 mm, sharp, densely stiff-hairy; lemma hard, margins overlapping at maturity, upper portion fused, awn 6.5–18 cm, bent twice, lower segments twisted, last segment not twisted; palea = lemma, hard, 2-veined, veins terminating at tip
Species in genus: 4 species: North America
Etymology: (Greek: western stipa)
Segregated from Stipa ; most closely related to Piptochaetium, Nassella.

Native

H. comata (Trin. & Rupr.) Barkworth

NEEDLE-AND-THREAD


Stem 1–11 dm
Inflorescence 10–28 cm
Spikelet: lower glume 18–35 mm, upper 1–3 mm shorter; floret 7–13 mm; lemma evenly hairy, hairs ± 1 mm, white; awn 65–195 mm
Ecology: Well-drained soils
Elevation: 200–3500 m.
Bioregional distribution: Sierra Nevada, Transverse Ranges, Peninsular Ranges, Great Basin Floristic Province, Desert Mountains
Distribution outside California: to Yukon, Great Plains, Mexico
Synonyms: Stipa c. Trin. & Rupr.

Native

subsp. comata


Spikelet: awn 75–195 mm, distal segment wavy or curly
Chromosomes: 2n=38,44,46
Ecology: Grassland, sagebrush scrub
Elevation: 200–3500 m.
Bioregional distribution: Sierra Nevada, Transverse Ranges, Peninsular Ranges, Great Basin Floristic Province, Desert Mountains, introduced elsewhere
Distribution outside California: to Yukon, c US, Mexico
Flowering time: Jun–Jul
Horticultural information: DRN, SUN: 1, 2, 15, 16, 17 &IRR: 3, 7, 14, 18, 19, 20, 21, 22, 23, 24; also STBL.

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