The BioFiles - Bill Hubick

Sheep Laurel (Kalmia angustifolia)
Genus Kalmia Family Ericaceae Order Ericales Class Magnoliopsida Phylum Tracheophyta Kingdom Plantae Biodiversity

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Source: Wikipedia

Sheep-laurel
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Ericales
Family: Ericaceae
Genus: Kalmia
Species:
K. angustifolia
Binomial name
Kalmia angustifolia
Kalmia angustifolia L. — Sheep Laurel, Lambkill, Mauricie, Quebec, Canada

Kalmia angustifolia is a flowering shrub in the family Ericaceae, commonly known by various names including sheep laurel, wicky, and dwarf laurel. It is distributed in eastern North America from Ontario and Quebec south to Virginia,[1] while the southern subspecies K. angustifolia ssp. carolina grows as far south as Georgia.[2] It grows commonly in dry habitats in the boreal forest, and is also found in drier areas of peat bogs, or pocosins. It may become dominant over large areas after fire or logging.[3] Like many plant species of infertile habitats it has evergreen leaves and mycorrhizal associations with fungi.[4]

Description

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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 bumblebees and solitary bees. Each mature capsule contains about 180 seeds.[5]

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.[5] 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".[6] 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.[7]

Cultivation

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Kalmia angustifolia is cultivated as an ornamental garden shrub. It prefers a moist, acidic soil in partial shade. The species has gained the Royal Horticultural Society's Award of Garden Merit.[8] Numerous cultivars have been selected for garden use, of which K. angustifolia f. rubra,[9] with rich red flowers, has also won the award.[10]

Toxicity

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Kalmia contains a glycoside, known as andromedotoxin.[11] It is poisonous to mammals. Hence, it can be unwelcome in pastures.[12] Several of its folk-names testify to the plant's toxicity: 'lamb-kill', 'sheep kill', 'calf-kill', 'pig laurel', 'sheep-laurel' and 'sheep-poison'.[13] It is also known as narrow-leaved laurel and dwarf laurel.[13]

Southern sheepkill

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K. a. ssp. angustifolia (left) vs. K. a. ssp. carolina (right)

Carolina wicky, southern sheepkill, or Carolina bog myrtle is a shrub found from southeastern Virginia through Georgia. Originally classified as Kalmia carolina, authorities disagree on whether it should continue to be considered a separate species,[2] or whether it should be classified as a variety[14] or subspecies[15] of K. angustifolia. It is essentially allopatric with K. angustifolia ssp. angustifolia; their ranges only intersect in Southampton County, Virginia.[2] Aside from native range, the two types can be distinguished by the undersides of their leaves; southern sheepkill has a dense fuzz, absent from the smooth surface of sheep laurel.[16]

References

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  1. ^ "USDA Plants Database".
  2. ^ a b c "Kalmia carolina (Southern sheepkill)". Retrieved 29 July 2025.
  3. ^ 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.
  4. ^ Keddy, P.A. 2007. Plants and Vegetation: Origins, Processes, Consequences.Cambridge University Press, Cambridge, UK. 666 p.
  5. ^ 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.
  6. ^ Harrison, Lorraine (2012). RHS Latin for Gardeners. United Kingdom: Mitchell Beazley. ISBN 978-1845337315.
  7. ^ Blanchan, Neltje. 1917. Wild Flowers Worth Knowing Doubleday, New York.Project Gutenberg Literary Archive Foundation
  8. ^ "Kalmia angustifolia". www.rhs.org. Royal Horticultural Society. Retrieved 12 February 2020.
  9. ^ "RHS Plant Selector - Kalmia angustifolia f. rubra". Royal Horticultural Society. Retrieved 12 February 2020.
  10. ^ "AGM Plants - Ornamental" (PDF). Royal Horticultural Society. July 2017. p. 57. Retrieved 14 March 2018.
  11. ^ "Kalmia angustifolia, K. carolina". plants.ces.ncsu.edu. Archived from the original on 2019-05-03. Retrieved 2019-02-01.
  12. ^ "Kalmia angustifolia". www.fs.fed.us. Retrieved 2019-02-01.
  13. ^ a b "Kalmia angustifolia". Germplasm Resources Information Network. Agricultural Research Service, United States Department of Agriculture. Retrieved 24 December 2017.
  14. ^ "Kalmia angustifolia var. carolina". p. 483. Retrieved 28 July 2025.
  15. ^ Haines, A. (8 September 2010). "New Combinations in the New England Tracheophyte Flora". Botanical Notes. No. 13. Topsham, ME: Stantec. p. 4. Retrieved 28 July 2025.
  16. ^ . p. 482 http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250065665. Retrieved 28 July 2025. {{cite web}}: Missing or empty |title= (help)

Media related to Kalmia angustifolia at Wikimedia Commons

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