Alders are trees comprising the genus Alnus in the birch family Betulaceae.

Are birch and alder the same?

Alders and birches are both in the birch family (Betulaceae). You might say they're cousins -- different genera, with alders in the genus Alnus and birches in Betula.

What tree family is alder?

alder, (genus Alnus), genus of about 30 species of ornamental shrubs and trees in the birch family (Betulaceae). Alders are distributed throughout the Northern Hemisphere and in parts of western South America on cool wet sites at elevations up to 2,500 metres (8,200 feet).