Alnus rhombifolia, the white alder, is an alder tree native to western North America, from British Columbia and Washington east to western Montana, southeast to the Sierra Nevada, and south through the Peninsular Ranges and Colorado Desert oases in Southern California.

[3][4] While not reported in northern Baja California, it has been predicted on the basis of its climatic adaptation to occur there also.

[3] Alnus rhombifolia is primarily found in the chaparral and woodlands, montane, and temperate forests ecoregions.

The male catkins are pendulous, slender, 3–10 centimetres (1.2–3.9 in) long, yellowish, and produced in clusters of two to seven; pollination is in early spring, before the leaves emerge.

[5] The small winged seeds disperse through the winter, leaving the old woody, blackish 'cones' on the tree for up to a year after.