Psorothamnus arborescens |
Psorothamnus arborescens var. californicus |
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Mojave indigo-bush |
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Habit | Shrubs. | |||||||||||||
Stems | 3–10 dm, gland-dotted distally when young, glands prickle-shaped, hairy to glabrate. |
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Branches | irregular, stiff; sterile shoots often sharp-tipped. |
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Leaves | usually pinnate, sometimes unifoliolate distally, (0.3–)1–3.5(–5.5) cm; leaflets (1 or 3)5–11, blades ovate, obovate, lanceolate, linear, elliptic, rhombic-elliptic, rhombic-ovate, or linear-oblanceolate, 2–14(–17) mm, terminal leaflet seldom longer than laterals, surfaces gland-dotted abaxially, silky-strigulose, villous-tomentulose to glabrate, loosely hairy, or glabrous. |
0.3–3.5 cm; leaflets (1 or)5 or 7(or 9), blades linear-oblanceolate to narrowly elliptic, 2–12 mm, surfaces silky-strigulose. |
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Racemes | loose; rachis without thornlike tip in anthesis, (1–)1.5–12 cm; bracts subulate to linear, 2.5–4 mm; bracteoles present. |
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Flowers | calyx 5–9 mm, pilosulous to minutely puberulent, strigulose, silky-canescent, or glabrate, tube 3–4.5 mm, ribs prominent, broader adaxial intervals with 2 rows, narrower one with 1 row of 3–5 glands, lobes broadly lanceolate, triangular, or lanceolate, abaxial lobe often shorter; corolla indigo-blue to violet; banner flabellate to flabellate-ovate, 6.3–10 mm, base cuneate to auriculate, claw cuneate; wings oblong to oblong-ovate, 5.4–8.2 × 2.2–3.5 mm; keel obliquely obovate, 5.8–8.4 × 3.3–4.9 mm; stamens (5.5–)6.5–9.8 mm; filaments distinct to (3–)3.5–5.6 mm; anthers (0.8–)0.9–1.3 mm, connective not gland-tipped. |
calyx 5.2–6.9 mm, tube 3–4.2 mm, silky-canescent externally; corolla indigo blue; banner 6.3–7.8 mm; keel 5.8–6.4 mm. |
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Legumes | ovoid-ellipsoid or obliquely ellipsoid, 8–10 mm, with scattered blister-glands, glands not confluent, glabrous or sparsely villosulous. |
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Seeds | (4.7–)5–6 mm. |
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2n | = 10. |
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Psorothamnus arborescens |
Psorothamnus arborescens var. californicus |
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Phenology | Flowering late winter–spring. | |||||||||||||
Habitat | Stony, rocky, or sandy ground in creosote-bush scrub, regions transitional to oak-juniper-manzanita associations. | |||||||||||||
Elevation | 100–1100 m. (300–3600 ft.) | |||||||||||||
Distribution |
sw United States; nw Mexico
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CA |
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Discussion | Varieties 4 (4 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Variety californicus is known from the San Bernardino Mountains and adjacent desert regions. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 11. | FNA vol. 11. | ||||||||||||
Parent taxa | Fabaceae > subfam. Faboideae > Psorothamnus | Fabaceae > subfam. Faboideae > Psorothamnus > Psorothamnus arborescens | ||||||||||||
Sibling taxa | ||||||||||||||
Subordinate taxa | ||||||||||||||
Synonyms | Dalea arborescens | Dalea californica, Parosela californica, Parosela californica var. simplicifolia, P. arborescens var. simplicifolius | ||||||||||||
Name authority | (Torrey ex A. Gray) Barneby: Mem. New York Bot. Gard. 27: 33. (1977) | (S. Watson) Sutherland: Gandhi & Vincent, J. Bot. Res. Inst. Texas 14: 188. (2020) | ||||||||||||
Web links |