Kalmia latifolia is an
evergreen shrub growing 3–9 m (9.8–29.5 ft) tall. The leaves are 3–12 cm long and 1–4 cm wide. The flowers are hexagonal, sometimes appearing to be pentagonal, ranging from light pink to white, and occur in clusters. There are several named
cultivars that have darker shades of pink, red and maroon. It blooms in May and June. All parts of the plant are poisonous. The roots are fibrous and matted.[5]
Distribution and habitat
The plant is naturally found on rocky slopes and mountainous forest areas. It thrives in
acid soil, preferring a
soil pH in the 4.5 to 5.5 range. The plant often grows in large thickets, covering great areas of
forest floor. In the
Appalachians, it can become a tree but is a shrub farther north.[5] The species is a frequent component of
oak-heath forests.[6][7] In low, wet areas it grows densely, but in dry uplands has a more sparse form. In the southern Appalachians, laurel thickets are referred to as "laurel hells" because it is nearly impossible to pass through one.
Ecology
Kalmia latifolia has been marked as a pollinator plant, supporting and attracting
butterflies and
hummingbirds.[8]
It is also notable for its unusual method of dispensing its pollen. As the flower grows, the filaments of its
stamens are bent and brought into tension. When an insect lands on the flower, the tension is released, catapulting the pollen forcefully onto the insect.[9] Experiments have shown the flower capable of flinging its pollen up to 15 cm.[10] Physicist
Lyman J. Briggs became fascinated with this phenomenon in the 1950s after his retirement from the
National Bureau of Standards and conducted a series of experiments in order to explain it.[11]
Etymology
Kalmia latifolia is also known as ivybush or spoonwood (because Native Americans used to make their spoons out of it).[12][13]
The plant was first recorded in America in 1624, but it was named after the Finnish explorer and botanist
Pehr Kalm (1716–1779), who sent samples to
Linnaeus.
Despite the name "mountain laurel", Kalmia latifolia is not closely related to the true laurels of the family
Lauraceae.
Cultivation
The plant was originally brought to Europe as an
ornamental plant during the 18th century. It is still widely grown for its attractive flowers and year-round evergreen leaves. Elliptic, alternate, leathery, glossy evergreen leaves (to 5" long) are dark green above and yellow green beneath and reminiscent of the leaves of rhododendrons. All parts of this plant are toxic if ingested. Numerous
cultivars have been selected with varying flower color. Many of the cultivars have originated from the Connecticut Experiment Station in
Hamden and from the plant breeding of Dr. Richard Jaynes. Jaynes has numerous named varieties that he has created and is considered the world's authority on Kalmia latifolia.[15][16]
The wood of the mountain laurel is heavy and strong but brittle, with a close, straight grain.[21] It has never been a viable commercial crop as it does not grow large enough,[22] yet it is suitable for wreaths, furniture, bowls and other household items.[21] It was used in the early 19th century in wooden-works clocks.[23] Root
burls were used for pipe bowls in place of imported
briar burls unattainable during
World War II.[22] It can be used for handrails or guard rails.
The
Cherokee use the plant as an
analgesic, placing an
infusion of leaves on scratches made over location of the pain.[29] They also rub the bristly edges of ten to twelve leaves over the skin for
rheumatism, crush the leaves to rub brier scratches, use an infusion as a wash "to get rid of pests", use a compound as a
liniment, rub leaf ooze into the scratched skin of ball players to prevent cramps, and use a leaf salve for healing. They also use the wood for carving.[30]
Gallery
K. latifolia leaves and early buds
Flower buds
Beginning to bloom
Full bloom
Blooming and wilted flowers on the same flower head
Bee pollinating mountain laurel on Occoneechee Mountain
^Schafale, M. P. and A. S. Weakley. 1990. Classification of the natural communities of North Carolina: third approximation. North Carolina Natural Heritage Program, North Carolina Division of Parks and Recreation.
^Taylor, Linda Averill 1940 Plants Used As Curatives by Certain Southeastern Tribes. Cambridge, Massachusetts. Botanical Museum of Harvard University (p. 48)
^Hamel, Paul B. and Mary U. Chiltoskey 1975 Cherokee Plants and Their Uses – A 400 Year History. Sylva, N.C. Herald Publishing Co. (p. 42)