As the meeting ground of four major floristic provinces, Glacier's ecosystem supports a diverse array of plant species and plant communities. Many species and plant communities reach the edge of their range here. Glacier Park has 30 species that are "endemic" to the region, those with ranges limited exclusively to the northern Rocky Mountains. All but one of these occur in cold, open areas characteristic of harsh, post-glacial environments. Many are relics of the post-glacial age or occur here because the diverse combination of environmental conditions create unique micro-habitats. Three major North American watersheds arise from Glacier National Park (Arctic, Atlantic and Pacific). Two climate zones (Pacific Maritime and Prairie/Arctic) are separated by the Continental Divide. Biomes range from the lower elevation pacific cedar-hemlock forest to the high alpine tundra. Plant varieties change somewhat north to south as well because the north half of the park is in the rainshadow of the Whitefish Range. The cedar-hemlocks give way to drier Douglas fir and lodgepole pine forests in the North Fork, Flathead River drainage.Floristic Provinces
- Cordilleran [49%], including the southern and central Rocky Mountains as well as the Cascade Mountains of the Pacific Northwest
- Boreal [39%], similar to what one would find across Canada
- Arctic-Alpine [10%]
- Great Plains [1%]
Glacier National Park is home to at least 1,132 species of vascular plants (those containing vessels that conduct water and nutrients). There are 88 annual or biennial plant species and 804 types of perennial herbs. Included in these numbers are 127 non-native species. Sixty-seven vascular and 42 non-vascular plant species found in Glacier Park are listed as "sensitive" by the State of Montana.