Alnus rubra, the red alder,
is a deciduous broadleaf tree native to western North America.
Alnus rubra
Broken branch showing red weathered bark
Typical leaf discoloration caused by ozone pollution
Male catkins with tiny female catkins above
Alders are trees that compose the genus Alnus in the birch family Betulaceae. The genus includes about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few species extending into Central America, as well as the northern and southern Andes.
Alder
Female alder catkins after shedding their seeds
Alnus serrulata male catkins
Pollen