In several respects the flora of the Tetons is unique. The high mountains have constituted a plant-migration barrier which many forms could not cross; hence the range limit of a number of species is found here. Representatives from north, south, east, and west are in the region, this being the limit, in many instances, of their distribution. There are a number of plants typical of the central Rockies and a few known only to this range. Four life zones are recognized within the park, all occurring within a distance of less than 15 miles.

The flowering period begins in the park as soon as the ridges and flats are free of snow in May, and it continues until about August 15 in the Arctic-Alpine Zone. Hence, plants of at least one zone and usually of several may be seen blooming at any time in the spring or summer.

The evergreen trees (of which the lodgepole pine, limber pine, whitebark pine, Engelmann spruce, and alpine fir are most common) form an appropriate frame for the majestic Teton peaks and are reflected in the lakes which they encircle.