Alder (Alnus)
DESCRIPTION: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. While Alders are often seen with many trunks, they can, however, be trained when young to have only one.
A. 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.
A. 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.
POTTING:
Alders can be planted in the spring or fall in light shade or full sun, in moist or wet soil. The exceptions are A. cordata and A. glutinosa, which don't thrive in shallow, alkaline soil; A. cordata and A. incana do better in drier soil.
A. glutinosa can grow in very wet soil, even where there is standing water. Most plants do better in cooler climates than in hot, humid ones.
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.
PROPAGATION:
Seeds can be sown in finely raked soil 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.
SOME VARIETIES ARE:
A. cordata (Italian Alder)
A. glutinosa & var. laciniata, pyramidalis, Imperialis
A. hirsuta (Manchurian Alder)
A. incana (Speckled Alder) & var. pendula, aurea
A. japonica (Japanese Alder)
A. maritima (Seaside Alder)
A. rubra (Red Alder)
A. rhombifolia (White Alder)
A. spaethii.
Betula sp., birch. These photos show an old brown male inflorescence and green fruiting female inflorescences. These eventually would shatter into hundreds of winged fruitlets.
Information: based on http://www.botany.com