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Kalmia latifolia L.

Mountain-laurel

Habitat: Rocky or gravelly woods and clearings, sometimes swamps. [Conifer forest (forest, upland); Hardwood to mixed forest (forest, upland)]

Range: Florida to Louisianna, north to New England, and west to Indiana.

Aids to Identification: Kalmia latifolia is a moderate-sized, branched shrub with evergreen leaves. The unusual flowers consist of 5 petals fused into a pentagonal saucer. Ten small pouches ring the margin of the petals, and the authers fit tightly into these pouches. When an insect pollinator lands on the flower it trips the authers, causing them to spring forward and dust the insect with pollen. Kalmia latifolia has larger flowers (2-2.5 cm wide) and leaves (1-4 cm long) than the other laurels that occur in Maine.

Ecological characteristics: Limited to more temperate coastal belt in Maine. Many occurrences of mountain laurel succumb to winterkill or to shading by a dense overstory. Often planted as an ornamental.

Phenology: Flowers May-July.

Family: Ericaceae

Synonyms: None noted

Known Distribution in Maine: This rare plant has been documented from a total of 23 town(s) in the following county(ies): Cumberland, Hancock, Oxford, Penobscot, Sagadahoc, Washington, York.

Dates of documented observations are: 1890, 1930, 1968, 1970 (2), 1974, 1975 (6), 1976 (3), 1985 (3), 1989 (2), 1990, 1991 (2), 1995, 1998, 2002 (3)

Reason(s) for rarity: At northern limit of range; not rare southwards.

Conservation considerations: Mountain laurel requires moderate to full light to thrive, and populations in open woods have been known to decline as the forest matures and less light reaches the shrubs. Partial harvests, carried out with care for the existing plants, can be helpful.