

Blue Ash Fraxinus quadrangulata
Blue Ash is a perennial tree native to Canada and the lower 48 states. It grows to 63 ft. A keystone plant for native insects and the food web.
More about this plant
Fraxinus quadrangulata, the blue ash, is a species of ash native primarily to the Midwestern United States from Oklahoma to Michigan, as well as the Bluegrass region of Kentucky and the Nashville Basin region of Tennessee. Isolated populations exist in Alabama, Southern Ontario, and small sections of the Appalachian Mountains. It is typically found over calcareous substrates such as limestone, growing on limestone slopes and in moist valley soils, at elevations of 120–600 m (390–1,970 ft). Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 5 derived from its U.S. range
- Drought tolerance
- Moderate
- Shade tolerance
- Low
- Wet-soil tolerance
- Low waterlogging
- Height
- 63 ft
- Lifespan
- Perennial
- Foliage
- Deciduous broadleaf
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~149 caterpillar species
Fraxinus supports ~149 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 an exceptional genus.
Recorded feeding on Fraxinus in North America, including:
+ 8 more species → ↑ show fewer
How we know this (2) Methods & honest limits
A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.
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 (20) 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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