Western Bog Laurel - Kalmia polifolia


  • Kalmia glauca [PFAF]
  • Kalmia microphylla [E-flora]
  • Kalmia microphylla
    • subsp. occidentalis (Small) Roy L. Taylor & MacBryde [E-flora][PCBC2004]
    • var. occidentalis (Small) Ebinger [E-flora]
  • Kalmia occidentalis Small [E-flora]
  • Kalmia polifolia
    • subsp. microphylla (Hook.) Calder & Roy L. Taylor [E-flora]
    • subsp. occidentalis (Small) Abrams [E-flora]
    • var. microphylla (Hook.) Rehder [E-flora]

General 6-18 inches high.[WildPNW] spreads by layering and short rhizomes. [PCBC2004]
Lifecycle Evergreen.[PFAF] Perennial.[WildPNW]
Flowers In terminal 1- to 12-flowered clusters.[IFBC] Purple.[USDA][E-flora] The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees.[PFAF] Five petals are partially fused into an open cup. [WildPNW] corolla nearly cup-shaped or rotate containing 10 "pockets" in which the anthers are borne before maturing.[HNW] Flowers about 2cm across.[PCBC2004]
Fruits Five-valved capsules. [PCBC2004]
Leaves Evergreen, opposite, leathery.[IFBC][E-flora] "Deep green above, grayish and glandular-puberulent on the under surface..."[HNW] glandular dots on the underside.[PWOBC] Usually rolled under on edges.[WildPNW] Narrowly lance-shaped and conspicuously whitish and fine-hairy beneath.[PCBC2004] 0.5-6cm long.[HNW]
Habitat Cold peat bogs and other wet places[11, 200]. [PFAF] Peat bogs, wet peaty forests and meadows from the lowland through alpine zones.[IFBC][E-flora]
Range Frequent throughout BC. [E-flora]
Status Native.[E-flora]
Similar Species: "It is important not to confuse Ledum with the more toxic swamp-laurel (Kalmia polifolia) which grows in similar habitats. The leaves of the latter are smooth rather than hairy underneath, and it has pink, not white, flowers (Turner and Szczawinski, 1990)" [Turner&Kuhnlein]


Medicinal Uses


"An extract made from boiling the leaves in water was taken for spitting of blood, and was used to wash open sores and wounds which would not heal (Boas, 1966)." [Turner&Bell2]


"There is an initial burning of the lips, mouth, and throat with ingestion of the plants followed up to six hours later by salivation, nausea, severe vomiting, abdominal pain, watering of the mouth, eyes, and nose, loss of appetite, repeated swallowing, headache, low blood pressure, and drowsiness with convulsions, weakness, difficulty in breathing, and progressive paralysis of the limbs, followed by coma and death in the most severe cases." [CPPlantMush]


Cultivation: "Requires an acid humus-rich soil, succeeding in part shade[182] or in full sun in cooler areas. Prefers almost full sun[11]. Dislikes dry soils[182], requiring cool, permanently moist conditions at the roots[21]. Succeeds in open woodland or along the woodland edge[200]. A very cold-hardy plant, tolerating temperatures down to about -30°c[184]. A very ornamental plant[11], there are some named varieties[200]. Pruning is not normally necessary[200]." [PFAF]


"Seed - surface sow in late winter in a cool greenhouse in light shade[78, 113]. Prick out the young seedlings into individual pots as soon as they are large enough to handle. The seedlings are rather sensitive to damping off, so water them with care, keep them well-ventilated and perhaps apply a fungicide such as garlic as a preventative. Grow the young plants on in light shade and overwinter them in the greenhouse for their first winter[78]. Plant them out into their permanent positions in early summer. The seed is dust-like and remains viable for many years[113]. Cuttings of half-ripe wood, August in a frame. Very poor results unless the cuttings are taken from very young plants[11, 78]. Layering in August/September. Takes 18 months[78]. The plants can also be dug up and replanted about 30cm deeper in the soil to cover up some of the branches. The plant can then be dug up about 12 months later when the branches will have formed roots and can be separated to make new plants[200]." [PFAF]

Kalmia latifolia and related spp.; Plant considered very dangerous for herbal use." [CPPlantMush] Honey, when made by bees in the area where mountain laurel is grown, has been found to be poisonous. [KYP James] Delaware Indians used the leathery leaves of the closely related Mountain Laurel, K. latifolia to make a decoction to commit suicide. [KYP James] Kalmia angustifolia, Kalmia latifolia and K. microphylla; All parts contain andromedotoxin and diterpenoid resinoides. "Symptoms occur 6 hours after ingestion." "First aid; Emesis; activated charcoal; tea or coffee." [Brinker TBM]


Page last modified on Wednesday, July 10, 2019 1:55 PM