Astragalus americanus (Hook.) M.E. Jones
American milk-vetch (American milkvetch)
Fabaceae (Pea family)
Introduction to Vascular Plants
American milk-vetch (American milkvetch)
Fabaceae (Pea family)
Introduction to Vascular Plants
Species Information
General:
Perennial herb from a woody stem-base, often somewhat rhizomatous; stems solitary to several, erect, 30-100 cm tall, often hollow, mostly unbranched, the lowermost nodes leafless, greenish, glabrous or with sparse, long, soft, unbranched hairs.
Leaves:
Alternate, pinnately compound, 9-17 cm long, short-stalked; leaflets 9 to 17, egg-shaped to elliptic-oblong, rounded at the tip, sparsely hairy below, glabrous above, 2-6 cm long; stipules 1-3 cm long, oblong, not joined, bent downwards.
Flowers:
Inflorescence a loose, axillary raceme of 10 to 25 (40) nodding, pea-like flowers, the racemes 2-9 cm long on stalks equalling or shorter than the leaves; corollas (8) 10-15 mm long, white or yellowish-white, the keel-tip often purplish, the banner slightly longer than the wings, which are shorter than the keel; calyces bell-shaped, 4-5 mm long, glabrous except for the long, fringing hairs of the very short, triangular teeth.
Fruits:
Pods, ellipsoid-inflated, drooping on long (5-10 mm) slender stalks, membranous, shiny, glabrous or nearly so, 2-3 cm long, 1-chambered.
Illustration
If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.
Illustration Source: The Illustrated Flora of British Columbia
Ecology
Ecological Framework for Astragalus americanus
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)
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 |
||
|
Avg |
Min |
Max |
|
| Elevation
(metres) |
1065 | 79 | 2200 |
| Slope
Gradient (%) |
13 | 0 | 80 |
|
Aspect (degrees) |
163 | 1 | 352 |
| Soil
Moisture Regime (SMR) [0 - very xeric; 4 - mesic; 8 - hydric] |
4 | 3 | 7 |
| Modal
Nutrient Regime
Class |
C | ||
| #
of field plots species was recorded in: |
80 | ||
| Modal
BEC Zone Class |
BWBS | ||
|
All BEC Zones (# of stations/zone) species was recorded in |
BWBS(36), ESSF(9), ICH(1), IDF(6), MS(12), SBPS(3), SBS(2), SWB(3) | ||
|
Source:
Klinkenberg 2013
|
|||
Habitat and Range
Moist to mesic meadows, streambanks, thickets and forest openings in the montane and steppe zones; frequent in BC east of the Coast-Cascade Mountains; N to AK, YT and NT, E to PQ and S to SD, MT and CO.Status Information
Synonyms
Synonyms and Alternate Names:
Astragalus frigidus (L.) A. Gray p.p.
Astragalus frigidus var. americanus (Hook.) S. Watson
Astragalus frigidus var. gaspensis (Rouss.) Fernald
Phaca americana (Hook.) Rydb. ex Small