Yellowleaf Hawthorn Crataegus flava
Yellowleaf Hawthorn is a perennial tree native to the lower 48 states. It blooms Apr. A keystone plant for native insects and the food web.
More about this plant
Crataegus flava, common names summer haw and yellow-fruited thorn, is a species of hawthorn native to the southeastern United States from Virginia to Florida, west to Mississippi. Due to an error by Sargent the name C. flava was, and often still is, used for a different species C. lacrimata, which belongs to a different series, the Lacrimatae series. Flavae is another group of species that were thought to be related to the misidentified C. flava, and although it is now apparent that they are not related, the name of the group remains. Because the true identity of this species has only recently been discovered, the name is rarely used correctly. Individuals with red fruit occur; these have sometimes been assigned to a separate species, Crataegus senta. 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 ~168 caterpillar species
Crataegus supports ~168 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 Crataegus in North America, including:
+ 8 more species → ↑ show fewer
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 (15) Open & cited
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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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