Kalmia angustifolia

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Kalmia angustifolia Rubra.jpg
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Ericales
Family: Ericaceae
Genus: Kalmia
Species: K. angustifolia
Binomial name
Kalmia angustifolia

Kalmia angustifolia is a flowering shrub in the family Ericaceae, commonly known as sheep laurel. It is distributed in eastern North America from Ontario and Quebec south to Virginia.[1] It grows commonly in dry habitats in the boreal forest, and may become dominant over large areas after fire or logging.[1] Like many plant species of infertile habitats it has evergreen leaves and mycorrhizal associations with fungi.[2] It is also found in drier area of peat bogs.


The attractive small, deep crimson-pink flowers are produced in early summer. Each has five sepals, with a corolla of five fused petals, and ten stamens fused to the corolla. They are pollinated by bumble bees and solitary bees. Each mature capsule contains about 180 seeds.[3]

In the wild the plant may vary in height from 15–90 cm (6–35 in). New shoots arise from dormant buds on buried rhizomes. This process is stimulated by fire.[3] The narrow evergreen leaves, pale on the underside, have a tendency to emerge from the stem in groups of three. The Latin specific epithet angustifolia means “narrow-leaved”.[4] A peculiarity of the plant is that clusters of leaves usually terminate the woody stem, for the flowers grow in whorls or in clusters below the stem apex.[5]

Numerous cultivars have been selected for garden use, of which K. angustifolia f. rubra,[6] with rich red flowers, has gained the Royal Horticultural Society's Award of Garden Merit.[7]


Kalmia angustifolia is poisonous to mammals

Kalmia contains a glycoside, known as andromedotoxin. It is poisonous to mammals. Hence, it can be unwelcome in pastures.[citation needed] Several of its folk-names testify to the plant's toxicity: 'lamb-kill', 'sheep kill', 'calf-kill', 'pig laurel', 'sheep-laurel' and 'sheep-poison'.[8] It is also known as narrow-leaved laurel and dwarf laurel.[8]


  1. ^ Weetman, G. F. 1983. Forestry practices and stress on Canadian forest land. pp. 260–301. In W. Simpson-Lewis, R. McKechnie, and V. Neimanis (eds.) Stress on Land in Canada. Ottawa: Lands Directorate, Environment Canada.
  2. ^ Keddy, P.A. 2007. Plants and Vegetation: Origins, Processes, Consequences.Cambridge University Press, Cambridge, UK. 666 p.
  3. ^ a b Hall, I. V., Jackson, L. P. and Everett, C. F. 1973. The biology of Canadian weeds. 1. Kalmia angustifolia L. Canadian Journal of Plant Science 53: 865–873.
  4. ^ Harrison, Lorraine (2012). RHS Latin for Gardeners. United Kingdom: Mitchell Beazley. ISBN 184533731X. 
  5. ^ Blanchan, Neltje. 1917. Wild Flowers Worth Knowing Doubleday, New York.Project Gutenberg Literary Archive Foundation
  6. ^ "RHS Plant Selector - Kalmia angustifolia f. rubra". Royal Horticultural Society. Retrieved 20 May 2013. 
  7. ^ "AGM Plants - Ornamental" (PDF). Royal Horticultural Society. July 2017. p. 57. Retrieved 14 March 2018. 
  8. ^ a b "Kalmia angustifolia". Germplasm Resources Information Network (GRIN). Agricultural Research Service (ARS), United States Department of Agriculture (USDA). Retrieved 24 December 2017.