Kendrick L. Marr, Richard J. Hebda, and Elizabeth Anne Zamluk
The taxonomically difficult and ecologically and phytogeographically important genus, Calamagrostis, was examined for British Columbia (BC). Morphological characters were analyzed by Principal Components Analysis (PCA) to characterize taxa and to aid in the development of a new key. Eight native species (Calamagrostis canadensis, C. lapponica, C. montanensis, C. nutkaensis, C. purpurascens, C. rubescens, C. sesquiflora, and C. stricta) are confirmed to occur in British Columbia, of which C. montanensis, C. nutkaensis, C. purpurascens, C. rubescens, and C. sesquiflora are reliably distinguishable. Comparison of species distribution to regional climatic and vegetation history suggests that Calamagrostis nutkaensis and C. sesquiflora likely survived in coastal refugia during late Wisconsin glaciations. Calamagrostis purpurascens likely persisted beyond the glacial limits or within nunataks and then spread into previously glaciated sites. Two interior continental species, C. montanensis and C. rubescens, probably spread north and west from the unglaciated zone south of the Cordilleran and Laurentide ice sheets. Calamagrostis lapponica likely persisted north of the ice sheets, and then spread southward into high-elevation sites in northern and eastern BC. Calamagrostis canadensis and C. stricta probably survived south and north of the ice sheets, and then spread into the previously glaciated terrain.