T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Kalmia latifoli (Mountain laurel)

Kingdom:   Plantae
(unranked):        Angiosperms
(unranked):        Eudicots
(unranked):        Asterids
Order:       Ericales
Family:      Ericaceae
Genus:      Kalmia
Species:     K. latifolia
Binomial name: Kalmia latifolia
Common name: Mountain laurel, Ivybush, Spoonwood, Calico bush, American laurel 


  All parts of this plant are toxic if ingested. See paragraph lower down the page.


Kalmia latifolia is a small, multi-stemmed tree in the heather family, Ericaceae. It is native to Eastern North America. Kalmia latifolia is the state flower of Connecticut.
It typically grows as a dense rounded shrub growing to about 4.5 m tall.  In the wild in its original habitat it can grow up to 10 m tall.
Flowers appear during early summer in terminal clusters (corymbs to 15 cm across). Each flower (>2.5 cm across) is cup shaped with five sides and ranges in colour from rose to white with purple markings inside.
After flowering, brown fruits (4.8 mm dehiscent capsules) appear and they persist into winter.
The evergreen leaves are elliptic, alternate, leathery and are up to 127 mm long. They are a dark, glossy green above and are a yellow green on the underside.
Kalmia latifolia is notable for its unusual method of dispensing its pollen. As the flower grows, the filaments of its stamens are bent and brought into tension. When an insect lands on the flower, the tension is released, catapulting the pollen forcefully onto the insect. Experiments have shown the flower capable of flinging its pollen up to 15 cm.


  Warning.
All parts of Kalmia latifolia are toxic, especially the young shoots and leaves. The main toxin is      called andromedo toxin. This toxin acts on blood circulation by lowering the blood pressure. This leads to
drowsiness. The drowsiness allows the toxin to concentrate until it can attack the central nervous system. Convulsions occur, which can be quite severe, with death being preceded by a sort of creeping paralysis. The poison can be found in honey if apiarists have their hives near the plant.
The flowers are very attractive to children who are often made ill by trying to suck the sweet liquid out of the flowers. The nectar can induce vomiting, stomach pains and a runny nose. It is often enough to handle the flowers or leaves to receive a mild dose of ill effects. Whenever you handle mountain laurel you should be very careful about washing your hands.Kalmia latifolia can produce fatal results in animals that eat too much of the leaves and stems. Goats are particularly vulnerable as are small birds like budgerigars.

  





As the flower grows, the filaments of its stamens are bent and brought into tension. When an insect lands on the flower, the tension is released, catapulting the pollen forcefully onto the insect. Notice in this photo stamens are attached to the surface of the petals.