Robbins' Milkvetch Astragalus robbinsii
Robbins' Milkvetch is a perennial wildflower native to Alaska, Canada, and the lower 48 states. It blooms May – Aug. A host for pollen-specialist native bees.
More about this plant
Astragalus robbinsii is a species of milkvetch known by the common name Robbins's milkvetch. It is native to North America, where it is widespread with several varieties originating from different regions.A. r. var. alpiniformis is endemic to Oregon. A. r. var. fernaldii is known from Quebec and Newfoundland and Labrador. A. r. var. harringtonii is endemic to Alaska. A. r. var. jesupii is a rare variety known only from three locations on the Connecticut River in New Hampshire and Vermont and is a federally listed endangered species. A. r. var. minor, the most widespread variety, can be found in western North America and eastern Canada. A. r. var. occidentalis is a rare variety endemic to the Ruby Mountains of Nevada. A. r. var. robbinsii is endemic to Vermont. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 5 derived from its U.S. range
- Lifespan
- Perennial
- Flower colour
- White AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~15 caterpillar species
Astragalus supports ~15 caterpillar species.
Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is a moderate genus.
Recorded feeding on Astragalus in North America, including:
+ 8 more species → ↑ show fewer
✦ Bees specialist-bee host
Specialist native bees depend on it.
Some native bees are pollen specialists (oligolectic) — they raise young only on pollen from particular plant genera. Astragalus is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.
Related plants
More Astragalus →
How we know this (2) Methods & honest limits
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
McKenzie et al. assigned each species a flower colour with a GPT-4V vision model over iNaturalist photos. We use the confident tier plus a separately-labelled lower-confidence top-up (mostly inconspicuous green/brown flowers), and render it as a small tint — never as an asserted fact, and kept out of the written synopsis.
Honest limits: AI image inference (~87% expert agreement on the confident tier); a decorative, confidence-tiered indicator, not a measured trait.
Sources for this entry (19) Open & cited
Cite this page Open data, please attribute
PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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