These quick-growing trees are commonly known as Alders. They are natives of Europe, North America and Asia. Alders grow well in moist soil near ponds and other wet ground. Alders are often seen with many trunks; however, they can be trained when young to have only one. Alnus cordata (Italian Alder) is an attractive tree that grows from 30 to 50 feet high. Its glossy green leaves grow 2 to 4 inches across. Alnus rubra (Red Alder) is a handsome tree growing from 40 to 60 feet high. It is covered with 3- to 6-inch, dark green leaves that are rusty-gray beneath. It has light grayish-white bark. Alders produce catkins of yellowish-green flowers. Male and female flowers are produced on the same tree in the spring. The male catkins are 2 to 6 inches in length. In the summer, the female catkins become brown, cone-like fruit that persists on the branches most of the year. They can be used in dried floral arrangements.

They can be planted in the spring or fall in light shade or full sun, in moist or wet soil. The exceptions are Alnus cordata and Alnus glutinosa, which don't thrive in shallow, alkaline soil; Alnus cordata and Alnus incana do better in drier soil; Alnus glutinosa can grow in very wet soil, even where there is standing water. They do better in the cooler parts of the U.S. Pruning should be done in the winter or early spring. As the tree attains height, gradually remove the lower branches until the desired amount of clear trunk is obtained.

Seeds can be sown in finely raked soil outside, in March or April, or in containers filled with sandy soil in a greenhouse or frame in January. They should be spaced 6 inches apart at first and transplanted twice a year until they are put in their permanent positions. If the trees are to be planted in a forest, those that are 2 feet high should be used. Those used for lawn ornament can be larger when transferred. Suckers can also be detached and planted.

 Alnus cordata (Italian Alder);
 Alnus glutinosa & var. laciniata, pyramidalis, Imperialis;
 Alnus hirsuta (Manchurian Alder);
 Alnus incana (Speckled Alder) & var. pendula, aurea;
 Alnus japonica (Japanese Alder);
 Alnus maritima (Seaside Alder);
 Alnus rubra (Red Alder);
 Alnus rhombifolia (White Alder);
 Alnus spaethii.