Betula occidentalis Betula occidentalis Betula occidentalis, the water birch or red birch, is a species of birch native to western North America, in Canada from Yukon east to western Ontario and southwards, and in the United States from eastern Washington east to western North Dakota, and south to eastern California, northern Arizona and northern New Mexico, and southwestern Alaska. It typically occurs along streams in mountainous regions. It is a deciduous shrub or small tree growing to high, usually with multiple trunks. The bark is dark red-brown to blackish, and smooth but not exfoliating. The twigs are glabrous or thinly hairy, and
Betula pendula continues from a lateral bud. The species is monoecious with male and female catkins found in the same tree. Some shoots are long and bear the male catkins at the tip, while others are short and bear female catkins. The immature male catkins are present during the winter but the female catkins develop in the spring, soon after the leaves unfurl. The leaves have short slender stalks and are long, triangular with broad, untoothed, wedge-shaped bases, slender pointed tips and coarsely double-toothed, serrated margins. They are sticky with resin at first but this dries as they age leaving small white