Alnus
(from al, near, and lan, the bank of a river; general habitat of the genus). The Alder Tree. ORD. Betulaceoe. A genus of deciduous trees and shrubs. Flowers monoecious; barren ones in long drooping autumnal catkins, lasting through the winter; fertile ones, produced in spring, in oval catkins, resembling a fir-cone in shape, the fleshy scales of which become indurated and ligneous as they approach maturity. Leaves stalked, roundish, blunt. Propagated usually by seeds, which are gathered towards the end of October; they require to be well dried, in order that the cones do not become mouldy. The seeds are sprinkled lightly on the ground with the slightest possible covering. Towards the end of the year, the seedlings will be about 10in. high. They are then planted in rows 1 1/2ft. apart, and 6in. from each other, where they may remain for two years, after which they can be placed out in the situation where they are March; and, if it is designed to make a plantation of Alder, the young trees should be put in holes, made with an ordinary garden spade, about 9in. deep, and about 4ft. apart. They are also increased, but rarely, by cuttings, by suckers, and by grafting.
A. cordifolia (heart-shaped-leaved).* fl. greenish-brown. March and April, before the development of the leaves. l. heart-shaped, acuminate, dark green, and shining. h. 15ft. to 50ft. Calabria and Naples, 1820. A large, very distinct, and handsome round-headed tree. It grows rapidly in dry soil, and is one of the most interesting of ornamental trees.
A. firma (firm).* l. oval lanceolate, acuminate, sharply serrated, many-nerved. Japan. One of the most distinct of all the Alders. A. glutinosa (sticky)*. barren catkins long, large, and cylindrical, pendent, their footstalks branched. fertile catkins small, ovate, with deep red scales. Spring. l. roundish-cuneiform, obtuse lobed at the margin, and serrated, somewhat glutinous, downy in the axils of the nerves beneath. h. 50ft. to 60ft. Britain. The Alder affects moist and damp situations, and, as it grows quickly, it is a useful tree to plant in bare situations. It is valuable as a nurse to other trees by the sea-side.
A. g. aurea (golden).* l. golden colour.
A. g. incisa (incised).* Compact form, with leaves quite like those of common Hawthorn. SYN. A. g. oxyacanthifolia.
A. g. laciniata (cut).* l. oblong and pinnatifid, with the lobes acute. This has elegant drooping branches and Fern-like leaves, and is one of the best. A. g. oxyacanthifolia (sharp-prickled). Synonymous with A. g. incisa. A. g. quercifolia (Oak-leaved).* l. with a sinuate outline, like that of the common Oak. A very distinct form. The variety imperialis (=asplenifolia) slightly differs in its more or less lobed or cut foliage; A. g. variegata is a variegated form.
A. incana (hoary).* l. broadly oval or ovate, rounded at the base, sharply serrate, whitened, and mostly downy beneath. h. 8ft. to 20ft. North Temperate regions. This affects drier situations than our native A. glutinosa. A. viridis (green). fertile catkins slender stalked, clustered, ovoid. l. round oval or slightly heart-shaped, glutinous and smooth or softly downy beneath, serrate, with very sharp and closely set teeth. Mountainous regions of northern hemisphere.