A native of Corsica, the timber was used as piles to support the buildings of Venice. The foliage is dense with small heart-shaped leaves that are bright, glossy green, and have finely toothed margins. They remain on the tree into late fall or winter. Male and female catkins occur on the same tree and appear before the leaves in late winter to early spring . The pendent, brownish-yellow male catkins are three inches long while the greenish red female catkins are reddish green and ¼” long. Egg shaped, one inch long conifer-like cones develop in summer in groups of three. They appear black in the fall and winter as the seeds mature and are dispersed, and can remain on the tree for up to a year. Young bark is greenish gray with many lenticels and becomes light gray-brown with fissures and flat ridges as it matures. Italian alder fixes nitrogen and does well in difficult spots. It makes an excellent shelterbelt or windbreak and can be made into bonsai. Italian alder is a member of the birch family, Betulaceae, that also includes horn and hazels. The genus name, Alnus, is the classical Latin name for one of the genera. The specific epithet, cordata, comes from the Latin word cor, cordis meaing heart and refers to the shape of the leaves.
Type: Deciduous tree
Outstanding Feature: Attractive and fast growing
Growth Rate: Rapid
Bloom: Pendulous, brown-yellow male catkins three inches long and reddish-green female cones ¼ inch long are produced before the leaves emerge in late winter or early spring.
Size: 80’ H x 23’ W
Light: Full sun
Soil: Fertile, moderately moist, well-drained; more drought tolerant than other alders
Hardiness: Zones 5-7
Care: Prune to maintain shape in mid winter before the sap flows.
Pests and Diseases: None of significance but canker, chlorosis, powdery mildew, aphids, tent caterpillar, flea beetles and lace bugs can be a problem.
Propagation: Seed, hardwood cuttings in winter.