These leaves drop from trees such as bigleaf maple, black cottonwood, cascara, Indian plum, mountain ash, Pacific willow, red alder and vine maple. Alders constitute a primary phase in forest succession and are usually found in association with dense shrubbery. Their roots are interconnected. Red alder seedlings are intolerant of shade and will develop only in bountiful sunlight. Their leaves are easily recognized.
Vine maple is a deciduous species of lesser abundance.
They require much light and are frequently found in places where there is a gap in the forest canopy. Their branches are spread out and their trunks are often tilted to gain maximum exposure to sunlight. Coniferous trees are the climax species in forest succession. Eventually they shade out alder and other plant species. Western red cedar, western hemlock, Douglas fir and lodgepole pine are found on the mountain.