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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.



David J. Keil, Family Editor and author, except as specified

Annual to tree
Leaves basal or cauline, alternate to whorled, simple to compound
Inflorescence: 1° inflorescence a head, each resembling a flower, 1–many, generally arrayed in cymes, generally subtended by ± calyx-like involucre; flowers 1–many per head
Flowers bisexual, unisexual, or sterile, ± small, of several types; calyx 0 or modified into pappus of bristles, scales, or awns, which is generally persistent in fruit; corolla radial or bilateral (rarely 0), lobes generally (0)4–5; stamens 4–5, anthers generally fused into cylinder around style, often appendaged at tips, bases, or both, filaments generally free, generally attached to corolla near throat; pistil 1, ovary inferior, 1-chambered, 1-seeded, style 1, branches 2, generally hair-tufted at tip, stigmas 2, generally on inside of style branches
Fruit: achene, cylindric to ovoid, generally deciduous with pappus attached
Genera in family: ± 1300 genera, 21,000 species (largest family of dicots): worldwide. Largest family in CA. Also see tribal key to CA genera: Strother 1997 Madroño 44(1):1–28. See glossary p. 25 for illustrations of general family characteristics.



Stems ± tomentose
Leaves alternate and generally clustered in axils, linear to (ob)lanceolate, sometimes persisting as stiff spines, glabrous to tomentose
Inflorescence: heads discoid, axillary or in ± rounded, terminal clusters; involucre cylindric to hemispheric; phyllaries in 1–2 ± equal series, often keeled; receptacle naked
Disk flowers generally 4–8; corollas cream to yellow, lobes long, spreading; anther bases ± sagittate, tips obtuse or acute; style branches papillate to short-bristly, tips truncate to conic
Fruit obconic or fusiform, often angled; pappus 0 or of generally many bristles or slender scales
Species in genus: 10 species: w North America
Etymology: (Greek: 4 together, from 4-flowered heads of some)
Reference: [Strother 1974 Brittonia 26:177–202]
Esp flower buds TOXIC to sheep (toxicity poorly understood).


T. spinosa Hook. & Arn.

Plant < 10 dm, spiny
Stems tomentose
Leaves: main leaves 5–25 mm, tomentose, forming rigid, recurved spines; clustered leaves 3–15(25) mm, thread-like to ± oblanceolate, ± glabrous
Inflorescence: heads generally 1–2 in axils of previous year's growth; peduncles generally 5–30 mm, tomentose, bracted; involucre 8–12 mm, ± bell-shaped; phyllaries 4–6, oblong to ovate
Flowers 5–8; corollas 6–10 mm, ± yellow
Fruit 6–8 mm, densely long-white-hairy; pappus of ± 25 slender scales, 6–9 mm
Chromosomes: 2n=60
Ecology: Generally saltbush scrub
Elevation: 800–2400 m.
Bioregional distribution: s Modoc Plateau, n East of Sierra Nevada
Distribution outside California: to Oregon, Idaho, Montana, Wyoming, n New Mexico

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