Mountain Laurel Kalmia latifolia
Mountain Laurel is a perennial tree native to the lower 48 states. It grows to 6 ft and blooms Apr in full sun, with brown fruit. A host for pollen-specialist native bees.
More about this plant
Kalmia latifolia, the mountain laurel, calico-bush, or spoonwood, is a flowering plant and one of the 10 species in the genus of Kalmia belonging to the heath(er) family Ericaceae. It is native to the eastern United States. Its range stretches from southern Maine to northern Florida, and west to Indiana and Louisiana. Mountain laurel is the state flower of Connecticut and Pennsylvania. It is the namesake of Laurel County in Kentucky, the city of Laurel, Mississippi, and the Laurel Highlands in southwestern Pennsylvania. Wikipedia →
Growing & care
USDA PLANTS · TRY- Sun
- Full sun
- Soil & moisture
- Low moisture
- Soil pH
- 4.5–5.5
- Fertility need
- Low
- Adapts to
- Coarse (sandy), Medium (loam)
- Hardiness
- USDA zone 5+
- Drought tolerance
- High
- Shade tolerance
- Moderate
- Wet-soil tolerance
- Low waterlogging
- Height
- 6 ft
- Mature width
- ~ 5 ft wide DERIVED derived estimate — open-grown crown allometry (height × growth-form ratio); not a measurement
- Spacing
- 5–12 ft apart from USDA planting density
- Spread
- None — clumping
- Growth rate
- Slow
- Growth form
- Multiple stems
- Lifespan
- Perennial · long-lived
- Foliage
- Evergreen broadleaf · coarse texture
- Active growth
- Spring & summer
- Fruit
- Brown
- Flower colour
- Pink AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
- Propagate by
- Seed, Cuttings, Bare root, Container
- Seed starting
- No stratification needed
- Seeds ripen
- Spring – Summer seed-collection / harvest window
- In the trade
- Routinely available
- Deer browsing
- Low often deer-resistant
- Resprouts if cut
- Yes regrows after top-kill
Sow timing keys off your local last- and first-frost dates.
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~34 caterpillar species
Kalmia supports ~34 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 strong genus.
Recorded feeding on Kalmia in North America, including:
+ 8 more species → ↑ show fewer
✦ Bees specialist-bee host · 16 bee visitors
Specialist native bees depend on it.
Some native bees are pollen specialists (oligolectic) — they raise young only on pollen from particular plant genera. Kalmia is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.
16 native & managed bee species are documented visiting Mountain Laurel — the 12 most-recorded:
Wildlife & visitors 1 bird · 23 nectaring
Open records of who else uses Mountain Laurel — a generalist food-web signal, kept separate from the keystone Ecological Value.
Recorded eaten by 1 bird species (fruit, seed, browse):
23 adult butterfly & moth species are recorded nectaring at its flowers — the most-recorded:
Across 623 U.S. vegetation-survey plots that recorded Mountain Laurel, these catalog species turned up most often in the same plot — a real field co-occurrence signal, not a planting prescription.
Related plants
More Kalmia →
How we know this (5) 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.
For woody plants that have a height but no measured crown, we estimate width = height × a crown-to-height ratio fit for that plant’s form (conifers narrower than broadleaf trees, shrubs widest), calibrated on our measured open-grown crowns and capped at the largest one ever measured. A measured crown always wins; herbaceous plants get nothing (no anchor).
Honest limits: A coarse class-median estimate for garden-scale spacing, not a measurement; woody single/multi-stem forms only.
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 (41) 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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