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Thompson's dalea

smoke tree

Habit Shrubs. Trees, small, rounded, appearing shrublike when young.
Stems

4–9(–15) dm, gland-dotted when young, silky-pilosulous, hairs retrorse.

70(–100) dm, gland-dotted distally when young, glands orange, silvery-silky to glabrate.

Branches

divaricate;

sterile shoots sharp-tipped.

divergent;

sterile shoots sharp-tipped or thornlike.

Leaves

pinnate, (1–)1.4–3 cm;

leaflets 7–17(or 19), blades obovate, oblanceolate, linear-oblanceolate, or linear-oblong, 2–7 mm, terminal leaflet shorter than laterals, surfaces sparsely gland-dotted abaxially, strigulose, more strongly so adaxially.

unifoliolate, 0.2–2.2 cm, leaflet 1, blade oblanceolate or cuneate-oblanceolate, surfaces gland-tipped abaxially, strigulose.

Racemes

loose and open;

rachis not spine-tipped in anthesis, (1–)2–9 cm;

bracts ovate-elliptic, 0.6–1.5 mm;

bracteoles absent.

loose;

rachis with thornlike tip in anthesis, 1–4 cm;

bracts ovate, 0.5–8 mm;

bracteoles present.

Flowers

calyx 3.7–5 mm, pilosulous throughout, or tube glabrous, lobes pilosulous, tube 2.4–3.3 mm, ribs prominent, intervals each with 1–4 large glands, lobes ovate to oblong-ovate, abaxial lobe shorter;

corolla pink- to violet-purple;

banner (5.5–)6–8.4 mm, ovate to suborbiculate, base cuneate or cordate, claw linear;

wings oblong, 5.8–6.6 × 2.6–3.2 mm;

keel obovate, 5.6–6.7 × 3.4–3.8 mm;

stamens 6–7.7 mm;

filaments distinct to 2.5–3.5 mm;

anthers 0.8–0.9 mm, connective gland-tipped.

calyx 4.5–5.2 mm, silky-strigulose, tube 3–3.8 mm, ribs not prominent, intervals each with (0 or)1(or 2) large glands, lobes ovate, abaxial lobe shorter;

corolla indigo-blue;

banner obcordate, 6.4–7.5 mm, base auriculate, claw linear to cuneate;

wings broadly oblanceolate, 5.5–6.8 × (2.4–)3–4.5 mm;

keel obovate, 6.6–8.2 × 4.2–5.4 mm;

stamens 9.5–11.5 mm;

filaments distinct to 4.1–4.9 mm;

anthers 0.7–1.1 mm, connective gland-tipped.

Legumes

obliquely obovoid, 4–4.5 mm, with large glands distally, glabrous proximally, sparsely pilosulous distally.

obovoid, 3–4 mm, with several glands proximally, pilosulous distally.

Seeds

2.1–2.6 mm.

rarely 2, 3 mm.

Psorothamnus thompsoniae

Psorothamnus spinosus

Phenology Flowering late spring–mid summer (fall).
Habitat Rocky or sandy deserts, wetter areas.
Elevation -70–400 m. (-200–1300 ft.)
Distribution
from USDA
sw United States
[BONAP county map]
from FNA
AZ; CA; NV; Mexico (Baja California, Sonora)
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Leaves of Psorothamnus spinosus are not retained for long; most of the time, the tree crown consists of a rounded mass of silvery branches. In California, P. spinosus is known from the desert areas in the southeastern part of the state.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Leaflet blades obovate or broadly oblanceolate, 2–4(–5) mm; calyx tube usually glabrous, lobes pilosulous, sometimes pilosulous throughout.
var. thompsoniae
1. Leaflet blades linear-oblanceolate or linear-oblong, 3–7 mm; calyx usually pilosulous throughout.
var. whitingii
Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Psorothamnus Fabaceae > subfam. Faboideae > Psorothamnus
Sibling taxa
P. arborescens, P. emoryi, P. fremontii, P. kingii, P. polydenius, P. schottii, P. scoparius, P. spinosus
P. arborescens, P. emoryi, P. fremontii, P. kingii, P. polydenius, P. schottii, P. scoparius, P. thompsoniae
Subordinate taxa
P. thompsoniae var. thompsoniae, P. thompsoniae var. whitingii
Synonyms Parosela thompsoniae Dalea spinosa
Name authority (Vail) S. L. Welsh & N. D. Atwood: Great Basin Naturalist 35: 354. (1976) — (as thompsonae) (A. Gray) Barneby: Mem. New York Bot. Gard. 27: 25. (1977)
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