The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) evaluates rare plant and animal species, endemic to Canada, determining which are at risk of extinction. As of 2010, more than 600 species of plants and animals have been listed by COSEWIC as “special concern,” “threatened,” “endangered,” “extirpated” or “extinct.” Of these, just over 100 are plant species that have been specifically listed as endangered--meaning they are at high risk of extirpation (extinction in Canada) or extinction (worldwide).
White Bark Pine
Assessed by COSEWIC in 2010, the white bark pine (Picea albicaulis) is one of the newest additions to the endangered species list. This alpine tree grows almost exclusively at elevations of more than 7,700 feet, and can be found in mountainous regions of British Columbia, Alberta, Oregon, California, Montana, Wyoming and Idaho.
It grows to about 30 to 50 feet tall, with a twisted trunk, white bark and reddish cones. The tree plays an important ecological role, providing needles for wildlife bedding, as well as seeds that are eaten by nutcrackers, squirrels, rodents and grizzly bears. Factors that have led to the decline/endangerment of the white bark pine include an introduced disease (white pine blister rust), a native pest (the mountain pine beetle), forest fires and climate change.
White Lady’s Slipper
A species of orchid, white lady’s slipper (Cypripedium candidum) is native to parts of Eastern Canada and the United States. It is considered endangered throughout its range in Canada, as well as most of the U.S. states within which it is present. This flower grows to about 8 inches in height, with ribbed leaves and one flower (occasionally two flowers) per stem. Each flower consists of lateral petals that are yellow-green and spiraled, as well as a single lower petal that is white and shaped like a pouch or slipper (hence, the name). The biggest factor that has led to endangerment of white lady’s slipper is its habitat--primarily calcareous wet prairies--being developed into farmland. It also has little genetic diversity.
The dwarf sandwort (Minuartia pusillia) is a small herb, endemic to British Columbia and the Western United States. It grows to a maximum height of about 2 inches, with thin stems, small white flowers and egg-shaped fruit. This plant is one of the most at-risk endangered species in Canada; with a single British Columbian population of only 20 plants (at its peak), it is nearly extirpated. The single Canadian population of this plant may represent an important genetic distinction, as the nearest other population is in Southern Washington. The major threat to the dwarf sandwort in Canada is, obviously, its own limited prevalence. However, other threats include seagull digging and trampling by trespassing humans.