05/18/2026
Kalmia latifolia (a.k.a., Mountain Laurel), a broadleaf evergreen shrub, was designated the state flower of Pennsylvania in 1933 by Governor Gifford Pinchot.* According to Joan Jubela, writing for Penn State Extension, the native range of Kalmia latifolia “is the eastern United States, extending from southern Maine to Louisiana and northern Florida.”* Of the seven species in the genus Kalmia found in North America, Kalmia latifolia is considered the most prolific.”* It belongs the heath family (Ericacea) along with rhododendrons and blueberries.*
Blooming in late spring to early summer, “[t]he fused petals of mountain laurel’s florets are shaped like inverted parasols. They range from near white to a blush of pint, while their corollas include subtle markings that can reveal either cinnamon, scarlet, rose, or burgundy.”* The flowers also contain a remarkable bit of biological engineering: the anthers are touch-sensitive catapults.* ** As Joan writes, “[s]acs of pollen, attached to ten separate anthers, are nestled into the base of the bud that will open into the corolla. As the bloom swells, then opens, the filaments attached to each anther are pulled backward in an arc, creating a hair-like trigger. When a bumblebee begins to explore, the filament hurls the pollen at the underside of the bee.”*
While able to tolerate a variety of conditions, it prefers partial shade and moist, acidic, well-drained soil.**
To learn more about the species, check out the sources cited below!
Sources:
* “Mountain Laurel,” Joan Jubela (Master Gardener, Wayne County), Penn State Extension (updated July 5, 2023) (https://extension.psu.edu/mountain-laurel).
** “Kalmia latifolia,” North Carolina Extension Gardener Plant Toolbox, NC State Extension (accessed May 14, 2026) (https://plants.ces.ncsu.edu/plants/kalmia-latifolia/).
Photo taken at Longwood Gardens (May 28, 2022).
