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.



Annual to tree
Leaves generally compound, alternate, stipuled; leaflets generally entire
Inflorescence: generally raceme, spike, umbel or head; flowers sometime 1–2 in axils
Flowers generally bisexual, generally bilateral; hypanthium generally flat or cup-like; sepals generally 5, fused; petals generally 5, free, or the 2 lower ± fused; stamens 1–many, often 10 with 9 filaments at least partly fused, 1 (uppermost) free; pistil 1, ovary superior, generally 1-chambered, ovules 1–many, style, stigma 1
Fruit: legume, sometimes including a stalk-like base above receptacle, dehiscent, or indehiscent and breaking into 1-seeded segments, or indehiscent, 1-seeded, and achene-like
Seeds 1–several, often ± reniform, generally hard, smooth
Genera in family: ± 650 genera, 18,000 species: worldwide; with grasses, requisite in agriculture and most natural ecosystems. Many cultivated, most importantly Arachis , peanut; Glycine , soybean; Phaseolus , beans; Medicago ; Trifolium ; and many orns
Reference: [Polhill & Raven (eds) 1981 Advances in legume systematics; Allen & Allen 1981 Leguminosae]
Family description and key to genera by Duane Isely.


Duane Isely

Perennial, shrub, small tree, generally with thorns, gland-dotted
Stem generally intricately branched
Leaves odd-1-pinnate or simple
Inflorescence: raceme, sometimes spike- or head-like, axillary or terminal; pedicels generally with bractlets
Flower: calyx lobes generally unequal, upper pair often largest; petals all arising from receptacle, violet, blue, or 2-colored (purple and white); stamens 10, filaments partly fused; ovules generally 2
Fruit indehiscent, included in or exserted from calyx, generally glandular
Seed 1
Species in genus: 9 species: sw US, Mex
Etymology: (Greek: scabshrub)
Reference: [Barneby 1977 Mem New York Bot Garden 27:21–54, 598–607]


P. arborescens (A. Gray) Barneby

Shrub < 1 m, sometimes unarmed, glabrous to puberulent
Leaf: leaflets generally 5–7, linear to ovate, 3–10 mm, terminal (sometimes all) often continuous with axis
Inflorescence: raceme, open; pedicels with bractlets
Flower: calyx 5–9 mm, lobes ± equal, generally < tube; corolla 6–10 mm, violet-purple
Fruit exserted, 7–10 mm, glabrous or finely hairy, with large, scattered glands
Ecology: Desert mtns, slopes, canyons, flats, washes
Elevation: 100–1900 m.
Bioregional distribution: San Bernardino Mountains, East of Sierra Nevada, Mojave Desert
Distribution outside California: s Nevada, Mexico
Varieties similar morphologically, distinct geog. Close to P. fremontii , which might be considered to constitute two additional vars
Horticultural information: TRY.


var. arborescens


Leaf: leaflets lanceolate to ovate, larger 2.5 mm or more wide, upper often continuous with axis
Flower: calyx 7–9 mm, generally conspicuously hairy
Ecology: UNCOMMON. Desert, including mtns
Elevation: 400–800 m.
Bioregional distribution: sw Mojave Desert (Kern, San Bernardino cos.)
Distribution outside California: Mexico
Flowering time: Apr–May
Synonyms: Dalea a. (A. Gray) A. Heller; D. fremontii var. saundersii (Parish) Munz
See the CNPS Inventory for information about endangerment and rarity.
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bioregional map for PSOROTHAMNUS%20arborescens%20var.%20arborescens being generated

Retrieve Jepson Interchange Index to Plant Names entry for Psorothamnus arborescens var. arborescens
Retrieve dichotomous key for Psorothamnus
Overlay Consortium of California Herbaria specimen data by county on this map
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