

Glossy Buckthorn Frangula alnus
Glossy Buckthorn is an introduced perennial tree, found in Canada and the lower 48 states. It grows to 12 ft and blooms May – Jul.
More about this plant
Frangula alnus, commonly known as alder buckthorn, glossy buckthorn, or breaking buckthorn, is a tall deciduous shrub in the family Rhamnaceae. Unlike other "buckthorns", alder buckthorn does not have thorns. It is native to Europe, northernmost Africa, and western Asia, from Ireland and Great Britain north to the 68th parallel in Scandinavia, east to central Siberia and Xinjiang in western China, and south to northern Morocco, Turkey, and the Alborz in Iran and the Caucasus Mountains; in the northwest of its range, it is rare and scattered. It is also introduced and naturalised in eastern North America. Wikipedia →
Glossy Buckthorn is flagged invasive in the U.S. These natives fill a similar niche — same growth habit, bloom season, height, and region — so you keep the look and feed local wildlife instead of spreading a problem.
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 5 derived from its U.S. range
- Drought tolerance
- Low
- Shade tolerance
- Moderate
- Wet-soil tolerance
- Moderate waterlogging
- Height
- 12 ft
- Lifespan
- Perennial
- Foliage
- Deciduous broadleaf
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~11 caterpillar species
Frangula supports ~11 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 Frangula in North America, including:
+ 8 more species → ↑ show fewer
✦ Bees 22 bee visitors
22 native & managed bee species are documented visiting Glossy Buckthorn — the 12 most-recorded:
Wildlife & visitors 5 birds · 1 mammal · 9 nectaring
Open records of who else uses Glossy Buckthorn — a generalist food-web signal, kept separate from the keystone Ecological Value.
Recorded eaten by 5 birds and 1 mammal species (fruit, seed, browse):
9 adult butterfly & moth species are recorded nectaring at its flowers — the most-recorded:
How we know this (3) Methods & honest limits
We read each species’ measured specific leaf area (leaf area per unit dry weight) from the Global Spectrum dataset and band it: thin & fast (high SLA), medium, or thick & tough (low SLA). The global median is about 10 mm²/mg.
Honest limits: A species-mean from pooled measurements — individual plants vary with light and site. A broad strategy signal, not a precise per-plant figure.
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 (26) 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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