Northern Ontario Plant Database
Kalmia angustifolia L.
En: lambkill, sheepkill, wicky, sheep laurel, dwarf laurel, pig laurel, narrowleaf kalmia
Ericaceae (Blueberry Family)
General: An evergreen shrub, to 1 m tall, with rounded (terete) to 4-angled erect stems; spreading by woody, underground stems. Sheep laurel is easily recognized by the clusters of many distinctive, bright pink flowers borne below the new year's growth and its often whorled leaves. As one of it's common names (lambkill) implies, sheep have been killed by eating the poisonous leaves.
Leaves: In whorls of 3, or opposite. Leaves simple, pinnately-veined, somewhat stiff (coriaceous), short stalked, the petiole usually less than 1 cm long. Leaf blade elliptic-oblong; 2–5 cm long and 0.5–2 cm wide; dark green and somewhat shiny above, paler beneath, smooth (glabrous) or nearly so on both surfaces; base tapering (cuneate); apex blunt (obtuse) to pointed (acute); margins entire, flat to slightly curved under (revolute).
Flowers: Bisexual; in lateral clusters (corymbs) surrounding the stem, borne in the axils of the previous year's leaves and below the erect leaves of the current year's growth; blooming as the new leaves expand; flowers stalked. Calyx small, green, 5-lobed, the calyx and pedicels glandular-pubescent; petals 5, bright pink (rarely white), fused into a round, bowl-shaped (crateriform) corolla, to 1.2 cm across, slightly 5-lobed, with a deep red line encircling the ovary in the base of the corolla; stamens 10, with arching filaments, anthers caught in shallow pouches in the corolla, but abruptly released when tripped by pollinating insects; pistil 1, ovary superior, style straight, erect, 4–7 mm long. Flowers bloom in June and early July.
Fruit: Clusters of small, woody capsules, 2.5–4.5 mm in diameter, globose, pendant, maturing in early fall and persistent through winter.
Habitat and Range.: Dry to moist coniferous woods with poor, sandy to rocky soil, acidic barrens. Sheep laurel is native to eastern North America, ranging from central Labrador south to Georgia, and from Newfoundland west to northern Ontario, where its range extends north to the James Bay watershed (~52� N) and west to 87� W (Soper & Heimburger 1982); it is encountered less commonly west of the Timmins area.
Similar Species: There are several other low shrubs in northern Ontario that may be confused with sheep laurel based on their similar growth form, habitat, and leaf shape. Since these species all belong to the Blueberry Family (Ericaceae), they are referred to as ericaceous shrubs. The most similar in leaf shape is Rhododendron groenlandicum (Labrador tea), which can be distinguished from sheep laurel by its terminal cluster of white flowers and the rusty, woolly hairs on the lower surface of its opposite leaves.
There is one other species of Kalmia in northern Ontario, Kalmia polifolia (bog laurel), which is restricted to wet habitats, such as peatlands and wet woods. The bog laurel produces a terminal cluster of fewer flowers and has very stiff, narrowly elliptic, opposite, sessile leaves that are shiny and dark green on the upper surface, with recurved (revolute) margins, and a strongly whitened lower surface.
Internet Images: The Kalmia angustifolia webpage from the Wildflowers and Plants of the Upper Ottawa Valley website.
The Kalmia angustifolia webpage from the Connecticut Botanical Society.
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