see it clearly
Alder Tree (Alnus glutinosa)
The small order of catkin-bearing trees, the Betulaceae, includes only the two genera Betula, the Birches, and Alnus, the Alders. These are mainly distinguished by the character that, whilst in the Birch the scales constituting the fruit-bearing catkin are thin, and fall off simultaneously with the fruit itself, in the Alders these scales become thick and woody, and remain on the tree as a minute cone after the fruits have been discharged.
The few species constituting the genus Alnus are shrubs or trees, seldom reaching a large size, and range from Japan through Asia, to the north of the Himalayas, throughout Europe, North Africa, and North America, and along the Andes into Chili; and one representative of the group is confined to the Old World. Its distinctive feature is its leaves, which are roundish, with a wedge-shaped base, a wavy and slightly-toothed margin, and a short stalk, whilst they are hairy and glutinous when young--whence the specific name, A. glutinosa--and glossily dark olive green on both surfaces later on.
Though it may grow to a tree of considerable size, even reaching a height of seventy feet, and more than nine feet in girth, it does not usually exceed thirty or forty feet in height, or six feet in circumference, and is so commonly treated as coppice that it is most familiar to us in rounded clumps of a bushy habit, with several stems, none of which exceed half that size. Then it is that what beauty it possesses is revealed, as it grows, either with Willows or isolated, on the banks of streams in our midland or northern counties. Gilpin indeed speaks of it as growing in perfection on the banks of the Mole; but there are far finer specimens by many more northern streams. "He who would see the Alder in perfection," he writes, "must follow the banks of the Mole, in Surrey, through the sweet vales of Dorking and Mickleham, into the groves of Esher. The Mole, indeed, is far from being a beautiful river: it is a quiet and sluggish stream; but what beauty it has it owes greatly to the Alder, which everywhere fringes its meadows, and in many places forms very pleasing scenes, especially in the vale between Box Hill and the high grounds of Norbury Park."
In such situations our attention has often been called to the beauty of its rich masses of foliage as they overhang the golden beds of marsh-marigolds, or, later in the year, the foamy banks of meadow-sweet and the gorgeous magenta spikes of the loose-strife. Like all water-side plants, it retains its leaves longer than the deciduous trees of dry situations, keeping them sometimes until January; and, as they do not change color in autumn, its verdure is pleasing, even though the rigidity of its branches detracts from its gracefulness. Sir Thomas Dick Lauder justly supplements Gilpin's remarks with the observation that the Alder is as often associated with the more rugged scenery of the glens and ravines of Scotland, where it grows at an altitude of 1,600 feet, as with that of the tranquil alluvial vales of England. Some of the most striking individual trees, indeed, known to the present writer are some gnarled, crooked, and round-headed standard specimens, of no very exceptional size, in a mountain glen among the ancient Scots firs of the forest of Ballochbuie, near Balmoral.
Though it certainly flourishes best where its main roots are some little height above the water, the Alder is more tolerant of stagnant water around it than any other European tree; and from the dense mass of rootlets which it puts out in such situations, no tree is so well adapted for holding together the banks of rivers.
The bark of the larger stems is nearly black, and is full of clefts, as was noticed by Virgil in the passage which Dryden renders--
"As Alders in the spring the boles extend,
And heave so fiercely that their bark they rend."
Nor is there anything noticeable in the appearance of the ascending branches, so that, when leafless, the tree is not attractive. We may console ourselves, however, even amidst the comparative absence of beauty in the season of bare boughs; for if the grouping of branches is not beautiful in itself it is almost sure to appear so when the tracery of Nature's solid beamwork, and of her delicate lacework of twigs, is crystallized with hoar-frost. When, too, we see how our exotic evergreens suffer from the cold, and how the Yew-trees on the North Downs are bent towards the east by the westerly gales of autumn and winter, we can appreciate the provision of Nature by which the trees of the colder temperate regions are, as a rule, deciduous.
When in autumn the Alder-swamps are strewn with the newly-felled stems it will be seen that the live wood of the tree is white, but that it becomes red, as if with blood, where it is cut, and afterwards fades to a permanent pale pink. It is soft, with short fibres, giving it a homogeneous texture, and of moderate density, and is of exceptional durability if kept either perfectly dry or under water. It was used by the ancients for boats, possibly "dug-out" canoes; and Virgil stating that this tree formed the first material so employed, Professor Martyn suggests that a hollow Alder, falling into the stream on the banks of which it grew, may have given to man the first idea of a boat. Both Pliny and Vitruvius mention its employment for piles, the former also stating that it was used for water-pipes and for protecting river-banks, and the latter that the city of Ravenna was founded upon piles of its wood.
According to Evelyn, the celebrated bridge of the Rialto at Venice was similarly founded; and even down to the present day Alder-wood is used for piles in Holland. It loses about a third of its weight and a twelfth of its bulk in drying, but does not warp subsequently, so that it is suitable for turnery, carving, cabinet-making, clogs, sabots, and wooden platters. It has also been largely used for the staves of herring-barrels, and from its softness, which prevents it from splitting, it is recommended for wheel-barrows and stone-carts. Old trees with wood full of knots, when cut into planks, have all the beauty of the curled maple, with the color, though not the grain, density, nor luster of mahogany. The wood is, however, liable to the attacks of the larva of a small beetle, for which reason sabots made of this wood in France are hardened by smoking. It is also recommended to immerse Alder logs for some months in peat, to which lime has been added, and to varnish any furniture made from them. Being rich in tannin, the wood, if left long in peat, becomes as black as ebony, and when newly felled it takes a stain readily, so as sometimes to be used as a substitute for that wood; but it is far too soft to admit of the lustrous polish of so exceptionally dense a timber.
As fuel the Alder is far inferior in heating power to the Beech, but for this reason is useful for purposes where a slow heat is wanted. By far the chief use of the tree at the present day is for gunpowder-charcoal, for which purpose it is grown to a considerable extent, being only inferior to the Alder Buckthorn--the so-called "Dog-wood"--(Rhamnus Frangula) and to the White Willow (Salix alba). It is treated as coppice, and cut down every five or six years. The branches, which should be about four inches in diameter, are somewhat triangular in section, which gives a characteristic form to their small pith. The charcoal of the Alder is used for powder for heavy ordnance, or for the commoner commercial kinds.
The Alder is one of the woods which has of late been to some extent employed for paper-making. A ton of green wood yields three hundredweight of fiber, which bleaches fairly well, so as to be suitable for paper of various qualities.
From the time of Theophrastus the bark of the young shoots has been used for dyeing and tanning leather. When these shoots are less than a third of an inch in diameter their bark yields no less than sixteen per cent. of tannin. They produce red, brown, or yellow dyes if used alone, and black on the addition of copperas. The natives of Lapland are stated to use the Alder as a dye for their leathern garments, chewing its bark, and then employing their saliva, which becomes red in the process.
As final recommendations of the planting of this somewhat neglected tree in our swampy meadows, it may be mentioned that its boughs, from their durability in water, are especially suitable for filling in drains in wet land, and that it is exceptional in not in any degree injuring the grass that grows beneath it, either by its shade or by its fallen leaves. This last characteristic is alluded to by Browne in "Britannia's Pastorals," where he writes--
"The Alder, whose fat shadow nourisheth,
Each plant set neere to him, long flourisheth."
As in the allied Birch, the male and female catkins are in the Alder on the same tree. They appear before the leaves, the male ones being visible in autumn and the female ones being often conspicuous among the dark branches in March, whilst the leaves do not appear till the end of April or the first half of May. The male catkins are from two to four inches long, and of a dark red color, from the shield-like scales which protect the anthers and their pollen from rain and premature winds; whilst those bearing the female flowers are seldom an inch in length, and resemble miniature fir-cones of a reddish-brown hue. When the small winged fruits have been ripened and set free, the woody bracts hanging in catkins on the bare boughs still more forcibly suggest this resemblance.
The Alder can be reproduced either by layers, or by large cuttings, or "truncheons," two or three feet long. These it is recommended to leave during a winter and spring with their ends in water before planting. The tree is, however, preferably multiplied by seed. The cones should be gathered in dry weather, when their scales are beginning to open; and the seeds are best sown in November or December, in soil not exceptionally moist, and kept covered with pine needles, or other light dry litter, until April, when the seedlings will be fairly up. These may be transplanted in the nursery when a year old, and planted out at two years old.
The glossiness of its foliage gives the chief value to the Alder in a landscape. Folded in the bud like a fan, and enclosed by two pale-colored "stipules," the leaves are at first hairy, as well as glutinous. They can thus shoot off moisture that might induce decay in the buds, or subject them to the action of frost. By retaining their hairiness for some time the young leaves may also derive some advantage from the traces of ammonia in the dew; but when their cells become choked with the waste products of their digestive processes the now darker leaves become smooth. At all times they somewhat resemble those of the Beech, but are duller and darker in hue. In fact, the dark green of the tree and its compact growth in rounded masses render it somber and heavy when the sun is not on it. The cut-leaved variety gains considerably in lightness; but, though there are many trees more valuable and more beautiful, there is yet an undeniable charm belonging to the glossy clumps of the ordinary form. When we see it overhanging some stream or pool, contrasting with the blue-gray of the iris or the reed-mace, or with the gay flowers of the water-crowfoot or arrowhead, while the dab-chick or the water-vole find a home among its roots, or a temporary shelter beneath its boughs, the Alder forms by no means an unpleasing foil to its gay surroundings.