Vegetative cover varies widely; alpine environments contain various herbs, lichen and shrubs, whereas the subalpine regions are dominated by tree species such as Alpine Fir and Englemann Spruce. With decreasing elevation, the mountainous slopes and rolling plains split into three forest groups: a marginal band at upper elevations characterized by Engelmann Spruce, Alpine Fir and Lodgepole Pine; a second zone characterized by Ponderosa Pine, interior Douglas Fir, Lodgepole Pine and Trembling Aspen in much of the southwest and central portions; and another featuring western Hemlock, western Red Cedar, interior Douglas-fir, and western White Pine in the southeast.
The Englemann Spruce-Subalpine Fir belt occurs at elevations of between 1 200 and 2 300 metres. It forms a continuous cover at its lower and mid elevations and becomes subalpine parkland at its upper limits. Lodgepole Pine is widespread after fire and is predominant in the drier regions. Other common species include Whitebark Pine and Alpine Larch. Subalpine heather and grassy meadows are also common. Snow avalanche tracks are evident throughout much of the high-snowfall areas.
High-elevation forest gives way to one dominated by White Spruce, interior Douglas Fir and Lodgepole Pine at mid elevations of 400 to 1 500 metres. Where the precipitation is relatively high (up to 1 500 mm annually) an interior wet belt forms, dominated by tree cover of western Red Cedar and western Hemlock. This area is concentrated on the lower slopes of the Columbia Mountains and the windward side of the Rockies and much of the Shuswap and Quesnel highlands.
At lower elevations, particularly along dry valleys, Ponderosa Pine is dominant. Wildfires play an important role maintaining these forests. Stands are often open and park-like with an understorey of bluebunch wheatgrass. More moist sites are characterized by Douglas Fir, and water and paper birches, while the dry southern interior is devoid of trees and dominated instead by big sagebrush, rabbit-brush and antelope-brush. Grasslands featuring bunchgrasses and other grasses and shrubs appear in the valley bottoms and on plateaus in south-central B.C. from Riske Creek in the north to the Canada-U.S. border. Similar grasslands occupy smaller areas in the Kootenays of southeastern B.C.
The natural grasslands in this ecozone have not fared well. Most existing prior to European settlement have vanished, thanks to fire suppression, introduced species, and cattle grazing. Much of the grassland in the Okanagan Valley, for example, has been completely replaced by settlements, orchards, and crops. Today, introduced species have colonized many grasslands and the pockets of natural dry grasslands that survive are unique to Canada, dominated by species such as Bluebunch Wheatgrass that rarely occur east of the Rocky Mountains.
Extensive wetlands are infrequent in the mountainous portions of this ecozone. On slopes, wetlands are generally restricted to small transitional and non-forested bogs, marshes and skunk cabbage swamps. Much of the valley wetlands have been destroyed by urbanization and agriculture. Less than 15% of the original wetlands of the Okanagan Valley remains and is under constant threat from development.