This paper reports significant extensions of range for 71 vascular species and discusses the occurrence of several of these plants in relation to postglacial development of the flora of westcentral Alberta. Some attention is paid to the coniferous vegetation of the region, especially those faciations in which certain of the more interesting species occur. The alpine fir and black spruce faciations are regarded as edaphic climax types in the upland forest. Species new to Alberta include the "eastern"Rhynchospora capillacea, the rareSparganium glomeratum, and the "Pacific"Streptopus streptopoidesvar.brevipes. Two other "Pacific" species,Angelica genuflexaandTiarella trifoliata, previously known in the area from isolated collections, are now reported as widespread and locally abundant. Floristic data support the hypothesis of a fluctuating ice-free corridor as a refugium in western Alberta during the late Wisconsin or soon thereafter, and point to Manitobandash;Saskatchewanndash;Alberta as a vast meeting ground of "eastern" and "western" biota.
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