Woollypod Milkvetch
Astragalus purshii
- Native to:
- Canada, United States
Mark Groeneveld
Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Fabaceae
- Genus:
- Astragalus
- Species:
- Astragalus purshii
- USDA Symbol:
- ASPU9
Growth Characteristics
- Life Cycle:
- Perennial
- Growth Habit:
- Forb/herb
- Height:
- 30 cm
- Light Requirements:
- Full Sun
- Drought Tolerance:
- High
- Bloom Months:
- apr,may,jun
- Bloom Colors:
- white, cream, yellowish
- Ground Cover:
- Yes
Wildlife Benefits
- Bees:
- ★☆☆☆☆ Documented bee visitation (GBIF)
- Caterpillars:
- ★☆☆☆☆ Recorded caterpillar host plant (HOSTS Database)
Keystone Species Ranking
- Pollen Specialist Bee Keystone:
- ★★★☆☆ Native pollen specialist bee species supported by this genus (NWF)
Host Plant for Caterpillars
Garden & Ecology Notes
- Wildlife Value:
- bees, native pollinators
- Deer Resistant:
- Yes
- Fire Ecology:
- Fire adapted — tolerates or benefits from fire
- Fire Notes:
- Resprouts from root crown after fire. Common in fire-adapted sagebrush steppe ecosystems with 20-50 year fire return intervals.
Soil Requirements
- Soil Type:
- sandy, well-drained, nutrient-poor soil
- pH:
- 6.0 - 8.0 (neutral to slightly alkaline)
- Drainage:
- excellent drainage required
- Moisture:
- dry to moderate
- Notes:
- Common in arid, rocky habitats
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 30–60 days
- Scarification:
- Seed coat scarification required before sowing
- Germination Time:
- 14–30 days
- Notes:
- Scarification improves germination rates. Seeds may germinate erratically even after treatment due to hard seed coat variability.
The above propagation data sourced from Claude AI
Pre-treatment: Seeds need to be scarified with fine grit sandpaper for 30-90 seconds until seed coat abrasion is observed under a microscope.
Establishment: Seeds mature uniformly on individual plants throughout late summer. The highest average germination was obtained under the 9/25° C temperature regime, corresponding to average temperatures in June. The plant is found throughout British Columbia, Alberta, and Saskatchewan in Canada, as well as throughout the western United States and arid to semi-arid regions of western North America in cold-desert communities. Pods grow low to the ground and must be hand collected.
Source: npn.rngr.net
ORGHPS Germination Guide: Sow @ 20°C. Seed germinates within 3 months Resents transplanting. Requires scarification. Nick or rub between sheets of sandpaper. Requires soaking. Place in warm water until seeds swell, usually 24-48 hours. Discard water and any seeds that remain floating. * put in deep pot; protect from damping off