In western Washington, the month of May is usually marked by vivid springtime blooms of Rhododendron. A lesser known member of the same family as Rhododendron (Ericaceae), Kalmia latifolia is native to eastern North America, and is one of our most spectacular broadleaf evergreen shrubs. Its attractive qualities no doubt led both Connecticut and Pennsylvania to choose Kalmia latifolia as their state flower. Growing up to 30’ in the wild, in cultivation Kalmia slowly reaches heights of 8 to 10 feet, with a similar spread. Kalmia generally bloom later that most Rhododendron and are a good way to extend the blooming season. When not in bloom, alternate glossy deep green leaves and rounded habit give clues to its affinity with Rhododendron and Pieris. In bud, Kalmia are a special treat well before the flowers open. In early spring the small buds are covered in fine hairs. As the buds expand they develop pronounced ridges that make them resemble the dots of frosting found on decorated cakes. This fascinating geometric quality is enhanced by their arrangement in flat clusters. Inflated Kalmia buds then open to reveal five-parted shallow cups about one inch across. These groups of flowers are three to six inches across and range in color from pure white to deep pink. Several cultivars are noted for uniquely banded or spotted markings in varying tones of red and pink on their inner flowers petals. Kalmia cultivars ‘Star Cluster’, ‘Olympic Wedding’, and ‘Minuet’ are especially desired by enthusiasts for these markings. The genus Kalmia was named by Carl Linnaeus for his pupil Peter Kalm who authored a famous 18th century book Travels into North America.1
Species: Kalmia latifolia
Common Name: Mountain Laurel, Calico Bush
Location: Grid 30-3E at the intersection of Arboretum drive and the south Woodland Garden trail
1. Bean, W.J. Trees and Shrubs hardy in The British Isles, eighth edition. London: The Royal Horticultural Society, 1978. Print.