European Alder
This is the common alder of Great Britain and central Europe southward,
growing chiefly along water courses, in boggy grounds and upon moist
mountain slopes; introduced into the United States and occasionally
escaping from cultivation; sometimes thoroughly established locally. In
Medford, Mass., there are many of these plants growing about two small
ponds and upon the neighboring lowlands, most of them small, but among
them are several trees 30-40 feet in height and 8-12 inches in diameter
at the ground, distinguishable at a glance from the shrubby native
alders by their greater size, more erect habit, and darker trunks.