Kalmia latifolia, commonly called Mountain-laurel or Spoonwood, is a species of flowering plant in the blueberry family, Ericaceae, that is native to the eastern United States. Its range stretches from southern Maine south to northern Florida, and west to Indiana and Louisiana. Mountain-laurel is the state flower of Connecticut and Pennsylvania. It is the namesake of the city of Laurel, Mississippi (founded 1882).
It is an evergreen shrub growing to 3–9 m tall. The leaves are 3–12 cm long and 1–4 cm wide. Its flowers are round, ranging from light pink to white, and occurring in clusters. There are several named cultivars today that have darker shades of pink, near red and maroon pigment. It blooms in May and June. All parts of the plant are poisonous. Roots are fibrous and matted.
The plant is naturally found on rocky slopes and mountainous forest areas. It thrives in acidic 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 North America it can become tree sized on undeveloped mountains of the Carolinas but is a shrub farther north. The species is a frequent component of oak-heath forests. 
It is also known as Ivybush, Calico Bush, Spoonwood (because native Americans used to make their spoons out of it), Sheep Laurel, Lambkill and Clamoun.
The plant was first recorded in America in 1624, but it was named after Pehr Kalm, who sent samples to Linnaeus in the 18th century.
 Cultivation and uses
The plant was originally brought to Europe as an ornamental plant during the 18th century. It is still widely grown for its attractive flowers. 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. 
Wood railing section made with mountain laurel branches
The wood of the mountain laurel is heavy and strong but brittle, with a close, straight grain. It has never been a viable commercial crop as it does not grow large enough yet it is suitable for wreaths, furniture, bowls and other household items. It was used in the early 19th century in wooden-works clocks. Burls were used for pipe bowls in place of imported briar burls. It can be used for handrails or guard rails.
Mountain laurel is a food plant of last resort for gypsy moth caterpillars, utilized only during outbreaks when moth densities are extremely high.
Mountain laurel is poisonous to several different animals due to andromedotoxin and arbutin, including horses, goats, cattle, sheep, deer, and monkeys and humans. It is not toxic to dogs, cats, or small household pets. The green parts of the plant, flowers, twigs, and pollen are all toxic, including food products made from them, such as honey. Symptoms of toxicity begin to appear about 6 hours following ingestion. Symptoms include irregular or difficulty breathing, anorexia, repeated swallowing, profuse salivation, watering of the eyes and nose, cardiac distress, incoordination, depression, vomiting, frequent defecation, weakness, convulsions, paralysis, coma, and eventually death. Autopsy will show gastrointestinal irritation and hemorrhage.
K. latifolia flower buds.
More mature buds of wild K. latifolia, showing the geometry.
Flowers, both blooming and wilted, on the same flower head.
 See also
- ^ a b Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. New York: Charles Scribner's Sons. pp. 186–189.
- ^ The Natural Communities of Virginia Classification of Ecological Community Groups (Version 2.3), Virginia Department of Conservation and Recreation, 2010
- ^ 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.
- ^ Shreet, Sharon (April-May 1996). "Mountain Laurel". Flower and Garden Magazine. http://findarticles.com/p/articles/mi_m1082/is_n2_v40/ai_18152569/.
- ^ Jaynes, Richard A. (1997). Kalmia: Mountain Laurel and Related Species. Portland, OR: Timber Press. ISBN 0881923672.
- ^ a b "Species: Kalmia latifolia". Fire Effects Information Service. United States Forest Service. http://www.fs.fed.us/database/feis/plants/shrub/kallat/all.html#BOTANICAL%20AND%20ECOLOGICAL%20CHARACTERISTICS. Retrieved 2011 Oct 03.
- ^ a b "Mountain Laurel". Wood Magazine.com. http://www.woodmagazine.com/materials-guide/lumber/wood-species-2/mountain-laurel/. Retrieved 2011 Oct 03.
- ^ Gene Galbraith (September 12, 2006). "The legacy of the Ogee Clock". http://www.oldandsold.com/articles02/article1104.shtml. Retrieved October 3, 2011.
- ^ Pader, James. "Wood Railing". http://awoodrailing.com.
- ^ a b c Russell, Alice B.; Hardin, James W.; Grand, Larry; Fraser, Angela. "Poisonous Plants: Kalmia latifolia". Poisonous Plants of North Carolina. North Carolina State University. http://www.ces.ncsu.edu/depts/hort/consumer/poison/Kalmila.htm. Retrieved 2011 Oct 03.
- ^ "Mountain Laurel". ASPCA. http://www.aspca.org/Pet-care/poison-control/Plants/mountain-laurel.aspx. Retrieved 2011 Oct 03.
- ^ a b "Poisonous Plants of the Southern United States". Agricultural Extension Services, University of Tennessee. January 1980. http://www.caf.wvu.edu/~forage/library/bulletins/poisonous%20plants.pdf. Retrieved 2011 Oct 03.
- ^ Horton, Jenner L.; Edge, W.Daniel (July 1994). "Deer-resistant Ornamental Plants". Oregon State University Extension. http://extension.oregonstate.edu/catalog/pdf/ec/ec1440.pdf. Retrieved 2011 Oct 03.
- ^ a b c d e f "Kalmia latifolia". University of Pennsylvania School of Veterinary Medicine. http://research.vet.upenn.edu/PoisonousPlantsofPA/Kalmialatifolia/tabid/5452/Default.aspx. Retrieved 2011 Oct 03.
- ^ "Grayanotoxin". Bad Bug Book. U.S. Food and Drug Administration. 05/04/2009. http://www.fda.gov/Food/FoodSafety/FoodborneIllness/FoodborneIllnessFoodbornePathogensNaturalToxins/BadBugBook/ucm071128.htm. Retrieved 2011 Oct 07