

Rusby's Goldenbush Isocoma rusbyi
Rusby's Goldenbush is a perennial shrub native to the lower 48 states. It blooms Jul – Oct. A host for pollen-specialist native bees.
More about this plant
Isocoma rusbyi, the Rusby's goldenbush or Rusby's jimmyweed is a North American species of plants in the family Asteraceae. It has been found in the States of Arizona, Utah, New Mexico, and Colorado in the southwestern United States. Some of the populations lie inside Grand Canyon and Petrified Forest National Parks, others in the Glen Canyon National Recreation Area. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 7 derived from its U.S. range
- Lifespan
- Perennial
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts Documented caterpillar host
Recorded feeding on Isocoma in North America, including:
+ 3 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. Isocoma is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.
How we know this (1) 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.
Sources for this entry (14) 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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