E-Flora BC: Electronic Atlas of the Flora of British Columbia

Astragalus purshii Douglas ex Hook.
woollypod milk-vetch (woollypod milkvetch)
Fabaceae (Pea family)

Introduction to Vascular Plants

© Virginia Skilton  Email the photographer   (Photo ID #25503)

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Distribution of Astragalus purshii
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Species Information

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General:
Perennial herb from a taproot and branching stem-base; stems prostrate, tufted or mat-forming, 5-10 cm long, greyish-woolly with unbranched hairs.
Leaves:
Alternate, pinnately compound, crowded, 2-15 cm long, white-woolly; leaflets 5 to 19, elliptic or oval to oblong, 5-20 mm long; stipules membranous, lanceolate, long-pointed, 3-15 mm long, usually exceeding the internodes, not joined at the base.
Flowers:
Inflorescence a short, axillary raceme of 2 to 10 pea-like flowers, the raceme-stalks from shorter to longer than the leaves, sometimes almost lacking, arching or lying on the ground in fruit; corollas yellowish-white to reddish-purple, 1-3 cm long, the banner longer than the wings and the blunt keel; calyces cylindric, 12-16 mm long, black- to grey-hairy, the narrowly lanceolate teeth 1/3-1/2 as long as the tube.
Fruits:
Pods, egg-shaped or narrowly ellipsoid, spreading, unstalked, 1-2.5 cm long, leathery, greyish-woolly, somewhat flattened, straight to curved, 1-chambered.
Notes:
Two intergrading varieties of this highly variable species are recognized in BC.

1. Flowers yellowish-white or pale lavender, the keels purple-tipped; pods nearly straight.................. var. purshii

1. Flowers reddish-purple; pods curved and strongly grooved............... var. glareosus (Dougl. ex Hook.) Barn.

Source: The Illustrated Flora of British Columbia

USDA Species Characteristics

Flower Colour:
White
Blooming Period:
Mid Spring
Fruit/Seed characteristics:
Colour: Black
Present from Spring to Summer
Source:  The USDA

Habitat / Range

Dry grasslands and sagebrush scrub in the steppe and lower montane zones; common in SC BC; E to AB and S to SD, ND, CO, NV and NE CA.

Source: The Illustrated Flora of British Columbia

Ecology

Ecological Framework for Astragalus purshii

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class

Minimum

Average

Maximum

Elevation (metres) 225 637 1535
Slope Gradient (%) 0 28 70
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
20 198 360
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
0 2 6
Modal Nutrient Regime
Class
C
Number of field plots
 species was recorded in:
120
Modal BEC Zone Class
BG
All BEC Zones (# of stations/zone) species was recorded in: BG(59), IDF(13), MS(2), PP(41)

Climate

The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is not evaluated, unknown or variable.

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References