Kalmia latifolia

Kalmia latifolia is an evergreen shrub growing {{convert|3-9|m|ft|abbr=on}} 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.{{cite book

| last =Keeler

| first =Harriet L.

| title =Our Native Trees and How to Identify Them

| url =https://archive.org/details/ournativetreesa02keelgoog

| publisher =Charles Scribner's Sons

| year =1900

| location =New York

| pages =[https://archive.org/details/ournativetreesa02keelgoog/page/n215 186]–189 }}

File:Mountain Laurel Kalmia latifolia 'Olympic Wedding' Leaves and Buds 2575px.jpg|K. latifolia leaves and early buds

File:Buberel unknown flower 12.jpg|Flower buds

File:Kalmia latifolia species.jpg|Beginning to bloom

File:Mountain Loral Flowers.jpg|Full bloom

File:Mountain Laurel Kalmia latifolia 'Olympic Wedding' Young Old Flowers 3264px.jpg|Blooming and wilted flowers on the same flower head

File:Bee on a mountain laurel on Occoneechee Mountain.jpg|Bee pollinating mountain laurel on Occoneechee Mountain

2015-06-07-17h21m33 (31791324900).jpg|Kalmia latifolia in North Smithfield, Rhode Island

File:Mountain Laurel Fruiting body.png|Mountain Laurel fruiting body

File:Illustration from The Natural History of Carolina, Florida, and the Bahama Islands by Mark Catesby, digitally enhanced by rawpixel-com 64.jpg of Kalmia latifolia is a botanical illustration.]]

Kalmia latifolia was named and described by the renowned Swedish botanist Carl Linnaeus in 1753.{{r|IPNI:279164-2}}{{sfnp|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/page/358410#page/403/mode/1up p. 391]}} In his description, Linnaeus referred to an earlier description and illustration of Chamaedaphne foliis published by the English naturalist Mark Catesby in 1743.{{sfnp|Catesby|1734–1747|loc=[https://www.biodiversitylibrary.org/item/126154#page/302/mode/1up p. 98, t. 98]}} Catesby's illustration was designated as the lectotype of Kalmia latifolia {{small|L.}} in 1993.{{sfnp|Reveal|2012|pages=13,24}}

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. The species is a frequent component of oak-heath forests.[http://www.dcr.virginia.gov/natural_heritage/ncTIIIe.shtml The Natural Communities of Virginia Classification of Ecological Community Groups (Version 2.3), Virginia Department of Conservation and Recreation, 2010] {{webarchive|url=https://web.archive.org/web/20090115181617/http://www.dcr.virginia.gov/natural_heritage/ncTIIIe.shtml |date=2009-01-15 }}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. 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.{{Cn|date=March 2025}}

Kalmia latifolia has been marked as a pollinator plant, supporting and attracting butterflies and hummingbirds.{{Cite web|title=Planting Guides|url=https://www.pollinator.org/pollinator.org/assets/generalFiles/OzarkBroadleafrx1FINAL_171017_085901.pdf|access-date=2022-01-29|website=Pollinator.org|language=en-US}}

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.{{cite web |url=http://www.fs.fed.us/global/iitf/pdf/shrubs/Kalmia%20latifolia.pdf |title=Kalmia latifolia L. |author=McNabb, W. Henry |website=United States Forest Service |publisher=United States Department of Agriculture |access-date=27 April 2015}} Experiments have shown the flower capable of flinging its pollen up to 15 cm.{{cite journal |last1=Nimmo |first1=John R. |last2=Hermann |first2=Paula M. |last3=Kirkham |first3=M. B. |last4=Landa |first4=Edward R. |title=Pollen Dispersal by Catapult: Experiments of Lyman J. Briggs on the Flower of Mountain Laurel |journal=Physics in Perspective |volume=16 |issue=3 |date=2014 |doi=10.1007/s00016-014-0141-9 |pages=383|bibcode=2014PhP....16..371N |s2cid=121070863 |url=https://zenodo.org/record/1232576 }} 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.{{cite journal |last1=Nimmo |first1=John R. |last2=Hermann |first2=Paula M. |last3=Kirkham |first3=M. B. |last4=Landa |first4=Edward R. |title=Pollen Dispersal by Catapult: Experiments of Lyman J. Briggs on the Flower of Mountain Laurel |journal=Physics in Perspective |volume=16 |issue=3 |date=2014 |doi=10.1007/s00016-014-0141-9 |pages=371–389|bibcode=2014PhP....16..371N |s2cid=121070863 |url=https://zenodo.org/record/1232576 }}

Kalmia latifolia is also known as ivybush or spoonwood (because Native Americans used to make their spoons out of it).{{cite web|last1=Harris|first1=Tony|date=11 August 2015|title=Mountain Laurel (Kalmia latifolia)|url=https://mycherokeegarden.com/2015/08/11/mountain-laurel-kalmia-latifolia/|access-date=22 February 2020|website=mycherokeegarden.com|publisher=WordPress}}{{cite web |title=Kalmia latifolia |url=http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c798 |website=missouribotanicalgarden.org |publisher=Missouri Botanical Garden |access-date=16 June 2018}}

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.

The Latin specific epithet latifolia means "with broad leaves" – as opposed to its sister species Kalmia angustifolia, "with narrow leaves".{{cite book |last=Harrison |first=Lorraine |title=RHS Latin for Gardeners |year=2012 |publisher=Mitchell Beazley |location=United Kingdom |isbn=978-1845337315 }}

Despite the name "mountain laurel", Kalmia latifolia is not closely related to the true laurels of the family Lauraceae.{{Cn|date=March 2025}}

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.{{cite web|title=Mountain Laurel |last=Shreet |first=Sharon |url=http://findarticles.com/p/articles/mi_m1082/is_n2_v40/ai_18152569/ |publisher=Flower and Garden Magazine |date=April–May 1996 |url-status=dead |archive-url=https://web.archive.org/web/20120526080142/http://findarticles.com/p/articles/mi_m1082/is_n2_v40/ai_18152569/ |archive-date=2012-05-26 }}{{cite book |last=Jaynes |first=Richard A. |title=Kalmia: Mountain Laurel and Related Species |publisher=Timber Press |location=Portland, OR |year=1997 |isbn=978-0-88192-367-4 |url-access=registration |url=https://archive.org/details/kalmiamountainla00jayn }}

In the UK the following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:

• 'Freckles'{{cite web | url = https://www.rhs.org.uk/Plants/77502/i-Kalmia-latifolia-i-Freckles/Details

| title = RHS Plantfinder – Kalmia latifolia 'Freckles' | access-date = 16 March 2018}} – pale pink flowers, heavily spotted

• 'Little Linda'{{cite web | url = https://www.rhs.org.uk/Plants/103060/i-Kalmia-latifolia-i-Little-Linda/Details

| title = RHS Plantfinder – Kalmia latifolia 'Little Linda' | access-date = 16 March 2018}} – dwarf cultivar to {{convert| 1|m|ft|abbr=on}}

• 'Olympic Fire'{{cite web | url = https://www.rhs.org.uk/Plants/47139/i-Kalmia-latifolia-i-Olympic-Fire/Details

| title = RHS Plantfinder – Kalmia latifolia 'Olympic Fire' | access-date = 16 March 2018}} – red buds opening pale pink

• 'Pink Charm'{{cite web|title=RHS Plant Selector – Kalmia latifolia 'Pink Charm'|url=https://www.rhs.org.uk/Plants/56794/Kalmia-latifolia-Pink-Charm/Details|access-date=26 September 2020}}

File:Kalmia latifolia Clementine Churchill.jpg|'Clementine Churchill' in the Real Jardín Botánico de Madrid

File:Kalmia latifolia Little Linda 0zz.jpg|'Little Linda'

File:Kalmia latifolia 'Minuet' kz01.jpg|'Minuet' in Christchurch Botanic Gardens

File:Kalmia latifolia 'Olympic Fire' 6471.jpg|'Olympic Fire' in the Dorothy Clive Garden, England

File:Kalmia latifolia Pinwheel 1zz.jpg|'Pinwheel' in Brookside Gardens, Maryland

File:mountain-laurel-handrail.jpg

The wood of the mountain laurel is heavy and strong but brittle, with a close, straight grain.{{cite web |url=http://www.fs.fed.us/database/feis/plants/shrub/kallat/all.html#BOTANICAL%20AND%20ECOLOGICAL%20CHARACTERISTICS |title=Species: Kalmia latifolia |work=Fire Effects Information Service |publisher=United States Forest Service |access-date=Oct 3, 2011}} 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.{{cite web |url=http://www.oldandsold.com/articles02/article1104.shtml |title=The legacy of the Ogee Clock |first=Gene|last=Galbraith |date=September 12, 2006 |access-date=October 3, 2011}} Root burls were used for pipe bowls in place of imported briar burls unattainable during World War II.{{cite web |url=http://www.woodmagazine.com/materials-guide/lumber/wood-species-2/mountain-laurel/ |title=Mountain Laurel |publisher=Wood Magazine.com |access-date=Oct 3, 2011|date=2001-10-29 }} It can be used for handrails or guard rails.{{Cn|date=March 2025}}

Mountain laurel is poisonous to several animals, including horses,{{cite web |url=http://www.aspca.org/Pet-care/poison-control/Plants/mountain-laurel.aspx |title=Mountain Laurel |publisher=ASPCA |access-date=Oct 3, 2011}} goats, cattle, deer,{{cite web |url=http://extension.oregonstate.edu/catalog/pdf/ec/ec1440.pdf |title=Deer-resistant Ornamental Plants |author=Horton, Jenner L. |author2=Edge, W.Daniel |date=July 1994 |publisher=Oregon State University Extension |access-date=Oct 3, 2011 |archive-url=https://web.archive.org/web/20120329045217/http://extension.oregonstate.edu/catalog/pdf/ec/ec1440.pdf |archive-date=2012-03-29 |url-status=dead }} monkeys, and humans, due to grayanotoxin{{cite web|url=https://www.fda.gov/Food/FoodSafety/FoodborneIllness/FoodborneIllnessFoodbornePathogensNaturalToxins/BadBugBook/ucm071128.htm |title=Grayanotoxin |work=Bad Bug Book |publisher=U.S. Food and Drug Administration |date=May 4, 2009 |access-date=Oct 7, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20100314133504/https://www.fda.gov/Food/FoodSafety/FoodborneIllness/FoodborneIllnessFoodbornePathogensNaturalToxins/BadBugBook/ucm071128.htm |archive-date=March 14, 2010 }} and arbutin.{{cite web |url=http://www.ces.ncsu.edu/depts/hort/consumer/poison/Kalmila.htm |title=Poisonous Plants: Kalmia latifolia |work=Poisonous Plants of North Carolina |last1=Russell |first1=Alice B. |last2=Hardin |first2=James W. |last3=Grand |first3=Larry |last4=Fraser |first4=Angela |publisher=North Carolina State University |access-date=Oct 3, 2011 |archive-url=https://web.archive.org/web/20130104141921/http://www.ces.ncsu.edu/depts/hort/consumer/poison/Kalmila.htm |archive-date=2013-01-04 |url-status=dead }} The green parts of the plant, flowers, twigs, and pollen are all toxic, including food products made from them, such as toxic honey that may produce neurotoxic and gastrointestinal symptoms in humans eating more than a modest amount. Symptoms of toxicity begin to appear about 6 hours following ingestion.{{cite web |url=http://research.vet.upenn.edu/PoisonousPlantsofPA/Kalmialatifolia/tabid/5452/Default.aspx |title=Kalmia latifolia |publisher=University of Pennsylvania School of Veterinary Medicine |access-date=Oct 3, 2011 |archive-date=April 15, 2012 |archive-url=https://web.archive.org/web/20120415141829/http://research.vet.upenn.edu/PoisonousPlantsofPA/Kalmialatifolia/tabid/5452/Default.aspx |url-status=dead }} 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. Necropsy of animals who have died from spoonwood poisoning show gastrointestinal hemorrhage.

The Cherokee use the plant as an analgesic, placing an infusion of leaves on scratches made over location of the pain.Taylor, Linda Averill 1940 Plants Used As Curatives by Certain Southeastern Tribes. Cambridge, Massachusetts. Botanical Museum of Harvard University (p. 48) 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.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)

{{Reflist|40em|refs=

{{IPNI |id=279164-2 |taxon=Kalmia latifolia |authority={{small|L.}} |access-date=3 March 2025}}

}}

• {{cite book |last1=Catesby |first1=Mark |title=The natural history of Carolina, Florida and the Bahama Islands |volume=2 |date=1734–1747 |publisher=self-published |location=London |url=https://www.biodiversitylibrary.org/item/126154#page/7/mode/1up |access-date=3 March 2025}}
• {{cite book |last=Linnaeus |first=Carl |author-link=Carl Linnaeus |title=Species Plantarum: exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas |year=1753 |publisher=Impensis Laurentii Salvii |location=Stockholm |edition=1st |url=http://www.biodiversitylibrary.org/bibliography/669#/summary |access-date=3 August 2023}}
• {{cite journal |last1=Reveal |first1=James L. |title=A nomenclatural summary of the plant and animal names based on images in Mark Catesby's Natural History (1729–1747) |journal=Phytoneuron 2012-11 |date=2012 |pages=1–32 |url=https://www.phytoneuron.net/PhytoN-Catesby.pdf |access-date=3 March 2025 |issn=2153 733X}}

• [http://www.ct-botanical-society.org/galleries/kalmialati.html Connecticut Botanical Society Profile: Kalmia latifolia] {{Webarchive|url=https://web.archive.org/web/20101121234659/http://www.ct-botanical-society.org/galleries/kalmialati.html |date=2010-11-21 }}
• [https://web.archive.org/web/20060523011108/http://www.cas.vanderbilt.edu/bioimages/species/frame/kala.htm Kalmia latifolia images at bioimages.vanderbilt.edu]

{{US state flowers}}

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latifolia

Category:Flora of the Appalachian Mountains

Category:Trees of Northern America

Category:Natural history of the Great Smoky Mountains

Category:Plants used in traditional Native American medicine

Category:Plants described in 1753

Category:Taxa named by Carl Linnaeus

Category:Symbols of Connecticut

Category:Symbols of Pennsylvania

Category:Garden plants of North America