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.



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.


Species in genus: 1 sp.: w North America
Etymology: (Greek: 2 numbers, from 2-flowered head)
Reference: [Morton 1978 North America Fl II 2:47–49]


D. howellii A. Gray


Annual generally < 4 cm, tufted, cobwebby at base, ± glandular above
Leaves opposite, 1–3 cm, short-petioled, oblanceolate to ovate, entire, clustered around heads
Inflorescence: heads discoid, generally in sessile clusters; involucre 4–6 mm, narrowly bell-shaped; phyllaries 2–3, each subtending a flower, ± fused at base, obovate, tip rounded, back convex; receptacle naked
Flowers 2–3; corollas 4–6 mm, tube and throat ± purple, lobes spreading, white to purple; anther bases sagittate, tips ± triangular; style branches ± flat, ± papillate, tip slightly expanded, rounded
Fruit ± 3 mm, cylindric, ribbed, glabrous; pappus bristles ± 20, 3–5 mm, plumose, fused at base
Chromosomes: 2n=14
Ecology: UNCOMMON. Dry volcanic soils
Elevation: 1600–2300 m.
Bioregional distribution: Modoc Plateau
Distribution outside California: to sw Idaho, nw Nevada
Horticultural information: TRY; DFCLT.
See the CNPS Inventory for information about endangerment and rarity.
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bioregional map for DIMERESIA%20howellii being generated

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