Two species of laurel occur in Deering, Kalmia angustifolia (sheep-laurel) and K. latifolia (mountain laurel).
Laurels are members of the plant family Ericaceae, along with blueberries, cranberries, rhododendron, azalea, trailing arbutus, Indian pipe, and many other plants that are common in our part of the world. The genus Kalmia was named by Linnaeus, in the 18th Century, in honor of one of his students, Peter Kalm, a Swedish-Finish botanist and naturalist who traveled and collected plants in the Americas during the 18th century.
Mountain laurel is a native North American evergreen, perennial shrub. It is common in acidic soils of the Appalachian Mountains, plateaus, piedmont, and coastal plains from southeast Maine to the Louisiana delta and north through Indiana and eastern Ohio to southern Quebec. It is found in the understory of conifer and hardwood forests, where it can form virtually impenetrable thickets, but it also forms dense cover on ‘balds’ at 4000 ft in the Appalachian Mountains. Typically the plant is a shrub, reaching 6 feet or so in height, but occasional ‘trees’ can reach 50 ft in height in the valleys of the Blue Ridge and Allegheny Mountains of the southern Appalachians. and can form dense thickets.
The species is fairly common in south central New Hampshire, often forming dense thickets in shaded forests. Here in Deering it is not difficult to find plants of mountain laurel, but Deering’s mountain laurel plants are mostly low growing with woody stems and form a more or less densely ground cover on the deeply shaded forest floor. I have never seen these plants to flower. In my wandering in Deering I have seen flowering mountain laurel at only one site, on a town-owned lot not far from where Manselville Brook enters the Contoocook River. At this site there are not more than a half dozen upright woody shrubs, about 6 feet tall. They flower in the middle of June.
The chief pollinators of mountain laurel are bumble bees and other bees. The sPtamens, which carry pollen, adhere to the petals under tension. When a bee enters the flower, the tension is released and the pollen is shot onto the furry bee. The pollen can be shot for as much as a foot, fertilizing other flowers. If the flower is not visited by a bee, the stamens can release pollen and self fertilize their flower.
Members of the Ericaceae have fungi – – mycorrhizae — associated with their root hairs. The morphology of the mycorrhizal association, and the fungi that associate with roots of members of the Ericaceae are different from tree mycorrhizae. Tree mycorrhizae tend to be mushrooms while the fungi that associate with roots of the Ericaceae are taxonomically distinct. The nature of the ericoid mycorrhizal association is the least understood of all of the mycorrhizal associations.
Green parts of the plant, flowers, twigs, and pollen are all toxic, including food products made from them. Although mountain laurel pollen does not affect bees, the honey made from the pollen may induce neurotoxic and gastrointestinal symptoms in humans eating more than a modest amount. Symptoms of toxicity begin to appear about 6 hours following ingestion. Humans, their pets and livestock are all affected. Sheep and goats will readily graze on mountain laurel, and horses will eat the plant if there is nothing else to eat. Even ruffed grouse that feed on the leaves are sometimes killed.
Mountain laurel is unrelated to the true laurels (Lauraceae), which are used in cooking. Please do not substitute a leaf of a Kalmia species (mountain laurel, bog laurel, sheep laurel) for a bay leaf (Laurus nobilis) in your cooking!
Mountain laurel is the official state flower of Connecticut and Pennsylvania.
Sheep laurel, Kalmia angustifolia, is a perennial shrub that can get to be 3 feet tall and up to 6 feet wide. It has ridiculously showy, pink flowers in clusters formed below the branch tips so that leaves usually form further along the stem, above the flowers. Flowering is from late spring into summer. Leaves are held in whorls of two or three and are 1.5- 2.5 inches long. The plant forms a tap root that can be 3 ft deep, and a dense network of roots. Sheep laurel is colonial and can form dense stands.
Sheep laurel is native to northeastern North America. It is found from Newfoundland and Labrador west through Ontario and occasionally as far south as Georgia. It is common in the eastern Great Lakes region, the St. Lawrence region, northern New England, and the Maritime provinces.
There are two varieties of K. angustifolia. The variety carolina occurs in Virginia, the Carolinas, Tennessee and Georgia.
Sheep laurel is adapted to a wide range of habitats. bogs, swamps, other wetlands, and alpine summits in the Adirondack region of upstate New York. Here in Deering I have seen sheep laurel along water’s edge at Black Fox Pond, in the Audubon Preserve, and in Deering Lake.
Like mountain laurel, sheep laurel foliage is toxic. On the other hand, it provides winter forage and cover for wild grouse and other birds.