CHAP. CIV.

BETUEa'cEjE. ,/LNUS.

1679

species we think only varieties, as we have indicated by

putting the letter g. in parentheses.

Description. The alder, in a wild state, even in favour-able situations, is seldom seen higher than 40 ft. or 50 ft.;but in uncultivated grounds, and in good soil near water,it will attain the height of 50 ft. or 60 ft., and upwards.

This is not only the case with the species, but with thevariety A. g. laciniata, which forms a handsome pyramidaltree; which, at Syon, has attained the height of 63ft.,and at Woburn Farm, near Chertsey, is still higher. Thebark of the common alder, in oldish trees, is nearly black,and full of clefts ; the colour of the wood is white beforethe tree is cut down; but, immediately on being cut, thesurface of the wound becomes of a deep red; soon fading,however, into the pale flesh-colour, which the whole ofthe w'ood of this tree, when cut down, takes when dry, andretains ever afterwards. The wood is homogeneous, tender,and without much tenacity. The branches, when theyare young, and the tree is in a state of vigorous growth,have a triangular form; but, when mature, they are round. The bark, at therising of the sap, separates from the wood with very great facility. Theleaves, when in the bud, are folded in the manner of a fan, very glutinous,and completely enclosed by two oblongstipules of a whitish green. They are from3 in. to 4 in. long, and nearly as broad.

The petiole is about 1 in. long, and pro-longed on the disk of the leaf, in the formof a very prominent nerve on the underside, from which proceed to the right andleft other prominent nerves, in each of theaxils formed by which is a little tuft ofcottony hair. The characteristics of theleaves of this species, as compared withthose of other species of the genus, andespecially of A. incana, is, that they arealways rounded at the summit, and neverpointed; though this distinction does nothold good when applied to some of thevarieties, such as A. g. laciniata. The leaves are of a deep dark green; and boththe young shoots and leaves are covered with a glutinous substance, more espe-cially in the early part of summer. The male catkins are cylindrical, like thoseof the birch, and appear in the autumn; while the female ones, which are onbranched footstalks, are of a short conical form, like a small fir cone, andare produced in spring along with the leaves. On Mount Caucasus, Pallasinforms us, the female catkins come out about the end of February; but, inthe north of Russia, in March and April. The rate of growth of the alder,in a favourable soil and situation, is about 2 ft. or 3 ft. a year for four orfive years; so that a tree 10 years planted will frequently attain the height of20 ft. or 25 ft.; and at 60 years the tree is supposed to have arrived atmaturity. The roots are creeping; and sometimes, but rarely, they throwup suckers. The shade and fallen leaves of this tree are not injuriousto grass.

Geography, History, $$c. The common alder is the most aquatic of Euro-pean trees, being found in wet swampy grounds, throughout the whole ofEurope, in situations too moist for even the willow and the poplar. Inmeadows, and by river sides in the plains,it becomes a considerable tree; butpn mountains, and in the most northerly parts of Sweden, it diminishes to ashrub. It is found in the west, east, and north of A si? and in the north of

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