FAMILY BETULACEÆ

Genus ALNUS, Linn.

SMALL water-loving trees of rapid growth. Leaves simple, deciduous, alternate, short stemmed. Flowers apetalous, monœcious, in catkins. Fruit woody, cone-like, oval, with 2 seeds on each scale.

KEY TO SPECIES

A. Flowers in autumn: (A. maritima) SEASIDE ALDER

AA. Flowers before leaves in winter or early spring.

B. Staminate catkins becoming 4 to 6 inches long.

C. Bark smooth, pale grey or white; tree with narrowly pyramidal head: (A. Oregona) RED ALDER

CC. Bark ridged, dark brown; tree with wide, open head: (A. rhombifolia) WHITE ALDER

BB. Staminate catkins becoming 2 to 3 inches long.

C. Leaves narrow, tapering to base and apex: (A. oblongifolia) LANCELEAF ALDER

CC. Leaves broad, oval, papery: (A. tenuifolia) PAPERLEAF ALDER

AAA. Flowers after the leaves in spring or summer: (A. Sitchensis) ALASKA ALDER

The genus Alnus includes twenty species of shrubs and trees, nine in North America, six of which are trees in habit and size. The largest and most important timber tree is the black alder of the Old World. Widely distributed by Nature and by man, this genus is the source of many hardy ornamentals adapted to damp soils.

“Alder, the owner of all waterish ground.”

Seaside Alder (Alnus maritima, Nutt.)—A round-topped tree 15 to 30 feet, with slender branches. Bark thin, smooth, light brown; twigs greyish. Wood soft, light brown, close grained. Buds acute, dark red, ¼ inch long, with silky pubescence. Leaves 3 to 4 inches long, oblong, ovate or obovate, acute at both ends, shining dark green above, pale green and dull beneath, edges set with fine incurving teeth; petioles short. Flowers autumnal, from buds of previous spring; monœcious; staminate catkins, golden, 1 to 2 inches long; pistillate, oblong, ⅛ inch long, with red tips of stigmas protruding from scales. Fruit , a woody, oval strobile, ripe a year after blooming; scales thick, shiny, each bears two flat, obovate, pointed nuts or seeds. Preferred habitat, borders of streams and ponds, near, but not actually on, seacoast. Distribution, eastern Delaware and Maryland, Indian Territory. Uses: Rarely planted, but deserving of cultivation for its glossy foliage and the beauty and unusualness of its golden catkins appearing in September.

The seaside alder divides with the witch hazel the distinction of bearing flowers and ripening fruit simultaneously in the fall of the year. They do not compete for popular favour, because the alder comes first, hanging out its golden catkins in clusters on the ends of the season’s shoots in August and September. Nothing is left of them when the witch hazel scatters its dainty stars along the twigs in October and November. The tiny pistillate cones of the alder are scarcely larger than the buds that keep them company.

The seaside alder grows well in the Arnold Arboretum, at Boston, flowering profusely, thus proving itself hardy in New England, and comfortable in dryer soil than it naturally chooses. It is quite worthy of the attention of those who seek for beauty and novelty of habit among little native trees.

The Oregon, or Red Alder (A. Oregona, Nutt.), is a large tree for an alder, sometimes 80 feet in height, with a narrow pyramid of drooping branches about a trunk that may exceed 3 feet in diameter. The smooth, pale grey bark of this tree sets it apart from other alders. The flowers and strobiles are large to match the tree; the ovate leaves are crenately lobed and finely cut toothed. They are lined with rusty pubescence, and are usually smooth and dark green above.

This is the alder of the Western coast that climbs mountains until it leaves the spruces behind, but reaches its greatest size about Puget Sound.

This is the alder of the Western coast that climbs mountains until it leaves the spruces behind, but reaches its greatest size about Puget Sound. From Sitka south through Washington and Oregon it lines the stream borders, and along the mountains it reaches as far as Santa Barbara in California. It loves also the cañon sides in the coast range.

The reddish-brown wood is beautifully satiny when polished. It is light and easily worked, and though weak and brittle is made into furniture. The Indians make “dug-outs” of the butts of large trees.

The White Alder (A. rhombifolia, Nutt.), equal in size to the preceding species, grows along the mountain streams from northern Idaho to southern California. It has a white scurf on its new shoots and the opening leaves are clothed with white hairs. Its wide sap wood is also white. The tree’s spring appearance probably justifies its name. The irregularly diamond-shaped leaves are sharply and finely cut on thin wavy margins. The wonderful thing about this tree is its blooming in January or February, hanging its conspicuous yellow catkins out while yet all other trees are asleep. Even in California this is a striking phenomenon along the mountain streams fringed with these trees.

The bark of the trunks of white alder is furrowed and dark brown. The trees need not be confused with the Oregon alder, if the trunk be examined.

The wonderful thing about this tree is its blooming in January or February, hanging its conspicuous yellow catkins out while yet all other trees are asleep.

The Lanceleaf Alder (A. oblongifolia, Torr.), whose name describes it well, comes up from the Peruvian Andes through Mexico, and is found at high altitudes along cañon sides in New Mexico and Arizona.

The Paperleaf Alder (A. tenuifolia, Nutt.)—A small tree with thin, firm-textured leaves, ovate in shape with laciniate lobes, twice saw toothed, one of the prettiest of the alders, is abundant in thickets along the headwaters of streams that rise in the Western mountains. It follows the various ranges from British Columbia to Lower California, Colorado and northern New Mexico.

Poets do not always realise their responsibility. The one who characterised the trees that fringed the sluggish streams and cover the “water galls” in England as “the water spungie alder, good for naught,” put into rhythmic form, too easy to remember, a stigma that brands a really picturesque and useful tree. The alder’s primary virtue is that it will thrive in places so boggy that even willows and poplars cannot grow there. Can any lover of English landscapes spare the alders from unsightly places whose lines they soften and whose baldness they conceal with billows of living green? “He who would see the alder in perfection must follow the banks of the Mole, in Surrey, through the sweet vales of Dorking and Wickleham, into the groves of Esher.”

The English people cherish an affectionate regard for their native black alder, a description of which follows. The hawthorns of their hedgerows are not more a part of the life of the people. John Evelyn expresses the sentiment when, after recounting the many practical uses of the tree and its wood, he adds two more: “The fresh leaves alone applied to the naked sole of the foot, infinitely refresh the surbated traveller”; and “The very shadow of this tree doth feed and nourish the grass that grows under it.”

The Black Alder (Almus glutinosa, Gærtn.), native of Europe, Asia and North Africa, is the most picturesque of water-loving trees, with its dark green, round or oblong leaves glutinous when they unfold in the spring. The trees are tall and erect, with dark trunks. The tallest sometimes reach 70 feet and have a trunk diameter of 3 feet. These giant alders are dignified, indeed, but the rank and file of the species are smaller trees. They hang out their long yellow catkin fringe on the bare twigs in earliest spring, a sight to repay a visit, even if it involved the wearing of rubber boots; and the little green knobs on the branching side stems grow by autumn into ripe cones, out of whose slits fall the little flat seeds.

Compared with oak and ash timber, alder is indifferent in quality and does not interest the lumberman, but there are special uses to which alder is always put. Growing in water, it seems to recognise its element; alder piles, water pipes, pumps and watering troughs kept always saturated last indefinitely. The piles of the Rialto in Venice and those of Amsterdam, according to ancient authorities, are of alder. Exposed to conditions of alternate wet and dry, the wood soon rots. It was a canny Scot who buried alder boards in a peat bog, in which lime was also thrown. This prevented the invasion of destructive insects, and turned the pinkish brown wood to the colour and hardness of mahogany. The grain of alder is smooth, fine and lustrous. It does not warp nor splinter. In the old days it was a wood for the boatbuilder. “Excepting Noah’s Ark, the first vessels we read of were made of alder.” Virgil gives a pretty glimpse of northern Italy in one of his Georgics: “And down the rapid Po light alders glide.”

Alder wood serves many cheap and common uses: for sabots and clogs, and wooden heels; truncheons, kneading troughs, barrel staves, bobbins, trays, hop poles, and the like. The bark and cones yield tannin used in tanning leather and in medicine, and a yellow dye which is also used in the making of ink. The best charcoal for gunpowder is made from willow and alder. Warty excrescences on old trees and twisted roots furnish the inlayer with small but beautifully veined and very hard pieces. Articles made of this once brought high prices.

One of the best uses to which alder is put is planting in hedges along borders of streams where their roots, closely interlacing, hold the banks against crumbling.

The black alder is most often met in horticultural forms in America. There is a variety with large, shining leaves and red veins and petioles. The daintiest varieties are those with finely cut leaves, of which imperialis, with fingered leaves like the white oak, is a good example.

The Hoary or Speckled Alder (Alnus incana, Willd.), native of both hemispheres, is a handsome tree of medium size in Europe and Asia, but it rarely rises above a shrub in America. It is second only to the black alder, from which it is easily distinguished, for its branches are speckled with white spots. Its leaves are pointed and lined with a hoary bloom; and there is nothing glutinous about the opening leaves and shoots. The wood is very similar to that of the other species.

Two Japanese species of alder have come into American gardens, both vigorous, large-leaved trees, of good size and excellent habit. Alnus Japonica has a pyramidal head of shinıng dark green foliage; Alnus tinctoria is round headed, with handsome foliage, and is proving hardy and rapid of growth in New England. A cardinal merit of these cultivated alders is that they thrive in ordinary garden soil.