Kalmia latifolia Ericaceae
Mountain Laurel KAL-mee-a lat-i-FO-le-a
- Broadleaf evergreen shrub, 7-15 ft (2.1-4.5 m) tall, similar spread, dense when young, but loose and open with age. Leaves simple, alternate, but appear irregularly whorled, elliptic to elliptic-lanceolate, 5-13 x 2-4 cm, leathery, entire, dark green above, yellowish below. Flowers are in terminal clusters, each flower is 5-sided and cup-shaped, 2-2.5 cm wide, 10 stamens which on first opening are held in little cavities (pouch) in the corolla (petals), when the pollen is ripe and bend in the filament is touched, the pollen carrying anthers are released (this mechanism facilitates insect pollination).
- Part shade to shade, acid, well-drained, cool soil.
- Hardy to USDA Zone 4 Native from Quebec and New Brunswick to Florida, west to Ohio and Tennessee.
- Dirr (1998, p. 527), "individually the most beautiful flower I know."
But the entire plant is poisonous, consuming even small amounts of the leaves can be fatal! Andromedotoxin and arbutin are responsible for toxicity. Andromedotoxin is a resinoid, its structure is not fully known.
Arbutin is a glucoside by hydroquinone (Poisonous Plants of Pennsylvania, [web site], Penn. Dept. Agriculture).
- Many cultivars, Dirr (1998) lists over 60, with flower colors varying
from white to pink-rose and deep rose. Some of the more common ones
- 'Elf' - compact form, pink buds, white flowers
- 'Hearts of Desire' - buds dark red, flowers burgundy
- 'Olympic Fire' - deep red buds, pink flowers
- 'Ostbo Red' - bright red buds, flowers deep pink
- Kalmia: after Peter Kalmia, Finnish student of Linnaeus. latifolia: broad-leaved (also a narrow-leaved species, K. angustifolia), both native to eastern US.
- Oregon State Univ. campus: behind Owen Hall (ECE) along north wall (plants show some differences in leaf color, flowers vary from light pink to rose-pink, are different cultivars).