An Occurrence of the Hawkweed-Leaved Saxifrage, Saxifraga hieraciifolia, in Southern British Columbia, and its Palaeobotanical Implications

Résumé

The Hawkweed-Leaved Saxifrage (Saxifraga hieraciifolia), normally found in the alpine tundra in the Arctic, has been collected at 445 m in parkland near Chase, British Columbia. The closest previously recorded occurrence was on the tundra of the Liard Plateau, northern British Columbia. The new occurrence indicates that this species had migrated at least as far south as northern Washington State before the Late Wisconsin glaciation. The latter eliminated the species in British Columbia, but a small population survived south of the glaciers and then, after deglaciation, it migrated north into southern British Columbia, but along the lower limit of the main Boreal Forest instead of above treeline.