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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.


A. Michael Powell

Perennial, shrubs
Leaves generally opposite; blade elliptic to triangular, margin entire to lobed
Inflorescence: heads discoid, solitary or in ± flat-topped cymes; phyllaries subequal, in 1–2(3) series; receptacle flat to conic, naked
Flowers 10–60; corollas ± white or blue to pink-tinged, cylindric (or throat wider)
Fruit 5-angled, generally 5-ribbed; pappus of 5–40 slender scabrous bristles, often easily detached
Etymology: (Latin: resembling Ageratum )
Reference: [King & Robinson 1987 Monogr Syst Bot Missouri Bot Garden 22:428–436]


A. occidentalis (Hook.) R.M. King & H. Rob.

Perennial; caudex woody, ± rhizomatous
Stem 1.5–7 dm, erect or ascending, ± green or purple, puberulent
Leaves generally alternate; blade ± triangular, ± serrate, glandular
Inflorescence: heads 8–10 mm, clustered; phyllaries puberulent
Flower: corollas ± white to blue
Fruit 3–3.5 mm
Chromosomes: 2n=34
Ecology: Common. Rocks
Elevation: 2100–3700 m.
Bioregional distribution: Northwestern California, High Cascade Range, Sierra Nevada, Warner Mountains, n East of Sierra Nevada, White and Inyo Mountains
Distribution outside California: to Washington, Idaho, Utah
Flowering time: Jul–Sep
Synonyms: Eupatorium o. Hook
Plants from SN are smaller than those from NCoR
Horticultural information: DRN, SHD: 2, 7, 8, 9, 10, 11, 14, 15, 16, 17, 18, 19, 20, 21; DFCLT.

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