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COSEWIC assessment and status report on the Bog Bird’s-foot Trefoil in Canada

Special Significance of the Species

Lotus pinnatus is not known to be currently collected for any purpose in Canada. Seed can be purchased online from an American seed company (Fraser pers. comm. 2003), presumably for horticultural use or for the restoration of disturbed sites. The species could also be tested for medicinal compounds. In southern California, the Kumeyaay Indians used a decoction of Lotus scoparius (common deerweed) leaves to treat coughs. The foliage of this species was fed to domesticated animals and was used with dry pine needles to line pits for roasting yucca. Lotus scoparius was also used by the Kumeyaay as a construction material to thatch houses (Southwest Centre for Environmental Research and Policy 2003). Guard (1995) reported that the seeds and foliage of L. pinnatus provide food for a variety of wildlife species and that the seeds are especially important to quail and small mammals.

The British Columbia populations of L. pinnatus are at the northern extent of the geographic range of the species. Isolated peripheral populations are often genetically and morphologically divergent from central populations. The ability of a species to adapt to changing ecological conditions and therefore, its long-term survival, may rest on the conservation of these genetically distinct peripheral populations (Lesica and Allendorf 1995).

As they form an interconnected series of subpopulations that can interbreed and form the central core of the species’ range in British Columbia, the populations of Lotus pinnatus at Harewood Plains are especially significant and worthy of conservation. An improved understanding of the ecological needs of individual rare species is necessary to ensure that introduced populations can persist. The protection of larger populations throughout the species’ range is necessary for maintaining genetic diversity and long-term persistence. Large populations also serve as seed sources for dispersal into available habitat.

The grassland meadow ecosystems in which L. pinnatus is found are unique. They have developed under a soil moisture regime found nowhere else in Canada and support a unique assemblage of plants, several of which have become rare. Grassland meadow complexes, and the indigenous species associated with them, have been extirpated from much of their historic range throughout western North America (Guard 1995).