Betula occidentalis (Water Birch) is a species in the Betulaceae family native to western North America. In California its distribution is somewhat patchy, being found in the southern Sierras, Siskiyu and Modoc counties. It typically occurs along streams in mountainous regions from 2,000 ft. to over 11,000 ft. It is a deciduous shrub or small tree growing to 10 meter high, usually with multiple trunks. The bark is dark red-brown to blackish, and smooth but not exfoliating. The twigs are smooth or thinly hairy and have prominent resinous glands but are odorless when scraped. The leaves are alternate, ovate to rhombic, 1-7 centimeter long and 1-4.5 centimeter broad, with a serrated margin and two to six pairs of veins, and a short petiole up to 1.5 centimeter long. The flowers are wind-pollinated catkins 2-4 centimeter long, the male catkins pendulous, the female catkins erect. The fruit is 2-3 centimeter long and 8-15 millimeter broad, composed of numerous tiny winged seeds packed between the catkin leafs. It is amenable to garden conditions and can be used outside its range in the wild. It has good fall color especially where fall weather is colder.