Kalmia L. (1753), in the family Ericaceae, contains 7 species from North America.

Description Trees to 12m, or shrubs. The leaves are usually alternate, sometimes opposite or in groups of 3, evergreen, narrowly ovate. The flowers are usually in umbels or short bunches, pink to red, purplish, or white. Sepals 5, petals 5, equal, joined nearly to the top, forming a saucer-shaped corolla. Stamens 10, the anthers pressed into pouches in the petals, opening by pores, the pollen sometimes sticky. Ovary superior. Carpels 5, fused, with numerous ovules; style long and curved. Pollination is by insects, usually bumblebees, which are heavy enough to spring the stamens and be dusted with pollen. The fruits are dry, rounded capsules with numerous seeds.

Key Recognition Features The pinkish flowers with anthers pressed into pouches in the petals.

Evolution and Relationships Kalmiopsis Rehd., with 1 species in Oregon, is closely related but does not have the anthers in pouches on the petals.

Ecology and Geography Kalmia latifolia L. prefers dry, rocky woods, where it can form an understorey beneath deciduous trees; the other species are mostly found in bogs and pine barrens. All are found today in North America, from Newfoundland and Hudson Bay to Alaska and southwards to Florida and Cuba; fossil Kalmia is reported from the lower Miocene in Germany.

Comment Kalmia latifolia, the mountain laurel or calico bush, is one of the most attractive of flowering shrubs, the flowers looking as if they are made of icing. Many new hybrids with larger and brighter red flowers with interesting markings have been raised in the United States. The wood is hard and smooth, sometimes used for turning. The genus was named by Linnaeus after his pupil Peter Kalm (1715–79), who spent 3 years from 1748 travelling in America. As well as collecting plants for Linnaeus, he wrote an interesting journal on the early settlers.