348 Records

A tall shrub or small tree native to eastern North America and common along streams and river banks throughout Maryland. Smooth Alder grows side by side with Gray Alder where their ranges overlap. Dense alder thickens are formed in suitable habitats.

Smooth Alder is similar to Gray Alder in several respects, but there are telltale differences. In both species, male (staminate) catkins and female (pistillate) catkins are present in winter, and the male catkins hang downward in both species. Also, in both species, the female catkins, which are much smaller than the male catkins, are red in color. In Gray Alder, however, the female catkins droop through the winter, whereas in Smooth Alder they are more erect. Another telltale difference is the bark: Smooth Alder's bark is smooth, whereas Gray Alder's bark is speckled with large, horizontal, linear lenticels. The leaf margins of Smooth Alder are finely serrate, compared with the coarser margins in Gray Alder. The mature fruit in both species is conelike and after releasing the seeds persists through the winter.

Look for clumps of stems in wet soils along streams, and persistent cone-like structures on the stems.

Host plant for the leaf beetles Calligrapha alni and Calligrapha apicalis. All alders form symbiotic relationships with a nitrogen-fixing bacterium that forms nodules on their roots and aids plant metabolism. In this respect, alders are similar to legumes and some other plants.