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KALMIA (kal’-mi-ah) – Mostly evergreen shrubs, native of North America, belonging to the Heath Family. Their leaves contain a poisonous principle that may prove fatal to sheep, goats and calves that browse on the plants. Some are among the best of broad-leaved evergreens for North gardens, and very valuable for ornamental plantings, especially when massed. They thrive best in partial shade in sandy or peaty soils not too dry, but will also grow out in the open and in loam if free of lime. In sunny places a continuous mulch is invaluable. Propagated by seed, cuttings of half-ripened wood under glass, layers, and grafting, but plants may be successfully transplanted from the wild.

Enemies

Two leaf-spotting diseases that look somewhat alike are controlled by destroying infected leaves and spraying plants three or four times from June to September with bordeaux mixture. One causes circular, grayish white or silvery spots with a reddish border; the other causes larger spots lacking the silvery center. The flower-pot disease of azalea (which see) also attacks Kalmia.

Principal Species

Kalmia latifolia (Mountain-laurel, Calico-bush) is one of the most beautiful of shrubs, and perhaps the best broad-leaved evergreen for N. gardens. It is the State flower of Conn. and Penna. The showy flowers are borne in terminal clusters, varying in color from white to deep rose, with purple markings inside. There are several named forms, of which var. polypetala with narrow petals is conspicuous. Var. myrtifolia is a dwarf form with small leaves.

angustifolia (Sheep-laurel, Lambkill) grows to about 3 ft., with narrow light green leaves, pale beneath. It has purple or crimson flowers borne in lateral clus ters. The common names were given because the leaves were thought to be especially poisonous to sheep; actually there is more evidence of the dangerous nature of the better known Mountain-laurel.

polifolia (Bog Kalmia), formerly Kalmia glauca, is a low straggling shrub, with leavers white beneath and rosy-purple flowers in terminal clusters. Var. microphylia is an alpine form from the Rocky Mountains, only a few inches high.