The red alder (Alnus rubra) is a tall deciduous tree, reaching twenty-five meters in height. It has thin bark similar to birch; thin, grey (instead of white), and thin like paper. It is frequently occupied by lichens, and has inner red bark. The leaves of the red alder are deciduous and alternately arranged, broad and elliptic. The margins are slightly rolled under 8and wavy, with blunt, coarse teeth. They can reach five to fifteen centimeters long and are dull green on top. The flowers it produces are small catkins, appearing before the leaves. The female catkins can reach two centimeters long, the males can reach five to twelve centimeters long. The fruits it bears are brown cones up to two centimetrs long, which overwinter with the branches of the tree. It prefers moist forests and stream banks.
