Trees Worth Knowing Part 12

=The Black Alder=

_Alnus glutinosa_, Gaertn.

Of the alders, the black alders of Europe is the largest and most important timber tree. Its range includes western Asia and northern Africa. It was introduced successfully into our Northeastern states in colonial times and has become naturalized in many localities. These trees sometimes reach seventy feet in height and a trunk diameter of three feet. Their dark green foliage, glutinous when the leaves unfold in the spring, ranks these giant alders among the beautiful and picturesque trees.

The lumberman esteems alder wood only for special purposes. It grows in water and its wood resists decay better than any other kind when saturated through indefinite periods. In the old days it was the wood for the boat-builder. The piles of the Rialto in Venice and along the ca.n.a.ls of Amsterdam and other Dutch cities are of black alder. Water pipes and troughs, pumps, barrel staves, kneading troughs, sabots and clogs were made of alder wood. The bark and cones are rich in tannin and a yellow dye used in making ink. Willow and alder make the best charcoal for gunpowder. Warty excrescences on old trees and twisted roots furnished the inlayer with small but beautifully veined and very hard pieces, beautiful in veneer work when polished. In America the black alder is often met in horticultural varieties. The daintiest are the cut-leaved forms, of which _imperialis_, with leaves fingered like a white oak, is a good example.

One of the best uses to which alders are put in Europe is planting in hedges along borders of streams, where their closely interlacing roots hold the banks from crumbling and keep the current clear in midstream.

No English landscape is more beautiful than one through which a little river winds, its banks and the boggy spots tributary to it softened by billows of living green. "He who would see the alder in perfection must follow the banks of the Mole and Surrey through the sweet vales of Dorking and Wickleham."

=Seaside Alder=

_A. maritima_, Nutt.

The seaside alder shares with the witch hazel the peculiar distinction of bearing its flowers and ripening its fruit simultaneously in the fall of the year. The alder comes first, hanging out its golden catkins in cl.u.s.ters 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 seaside alder follows stream borders near but not actually on the seacoast, through eastern Delaware and Maryland, but ranges comfortably on drier soil as far west as Oklahoma and is hardy in gardens and parks as far north as Boston, where it blooms profusely and is much admired for both flowers and glossy foliage through the late summer.

=Oregon Alder=

_A. Oregona_, Nutt.

The Oregon or red alder reaches eighty feet in height and its trunk may exceed three feet in diameter. This Western tree exceeds the Old World alder in size. The smooth, pale-gray bark reminds us of the beech and sets this tree apart from the white alder whose bark is brown and deeply furrowed. The flowers and cone fruits are very large.

The ovate leaves are cut-toothed and often lobed. This is the alder of the West Coast, largest where it comes down to the sea near the sh.o.r.es of Puget Sound, but climbing the mountains and canyon sides wherever there is water, from Sitka to Santa Barbara. The reddish brown wood is light, easily worked, and beautifully satiny when polished. In Washington and Oregon it is largely used in the manufacture of furniture. The Indian dug-outs are made of the b.u.t.ts of large trees.

THE SYCAMORES, OR b.u.t.tONWOODS

=The b.u.t.tonwood=

_Plata.n.u.s occidentalis_, Linn.

Our eastern b.u.t.tonwood is a tree to which, in America, we supply the name sycamore. Its European counterpart is the plane tree of the Old World. It is one of the easiest trees to recognize, for its most prominent trait is fairly shouted at us from a distance, whenever one of these trees comes within the range of our vision. The smooth bark that covers the branches is thin, very brittle, and has the habit of flaking off in irregular plates, leaving white patches under these plates that contrast sharply with the dingy olive of the unshed areas.

On old trunks the bark is reddish brown and breaks into small, irregular plates; but above, and out among the branches, the tree looks downright untidy, and as though it had been splashed with whitewash by some careless painter. (_See ill.u.s.trations, pages 102-103._)

White birches grow in copses in low ground, a whole regiment of their white stems slanting upward. But the ghostly sycamore is apt to stand alone along the river-courses, scattered among other water-loving trees. The tree is wayward in its branching habit, its twigs irregular and angular. When the leaves are gone, it is a distressed-looking object, dangling its seed-b.a.l.l.s in the wind until the central, bony cob is bare, the seeds having all sailed away on their hairy parachutes.

In the warmer South our b.u.t.tonwood is a stalwart, large-limbed tree of colossal trunk, that shelters oaks and maples under its protecting arms. And there are some large specimens on Long Island.

The b.u.t.tonwood leaf in a general way resembles a maple's, being as broad as long, with three main lobes at the top. The leaf stem forms a tent over the bud formed in summer and containing the leafy shoot of the next year. The leaf scar, therefore, is a circle and the leaf base a hollow cone. At first a sheathing stipule, like a little leafy ruffle, grows at the base of each leaf, but this is shed before midsummer.

=Oriental Plane=

_P. Orientalis_, Linn.

The oriental plane is almost as familiar a tree as our native species, for it is planted as a street tree in every city and village, and is a favorite shade and lawn tree besides. The city of Washington has set the example and so has Philadelphia. One third of the street trees of Paris are plane trees.

The chief merits of this tree immigrant are its perfect hardiness, its fine, symmetrical, compact pyramid, its freedom from injury by smoke and dust, and its rapid growth in the poor soil of the parkings of city and village. In leaf and fruit and bark-shedding habit, it is easily recognized as a sycamore, though in this species more than one ball dangles from each stem.

The exactions of city life limit the number of tree species that will do well. Our native sycamore patiently endures the foul breath of factory chimneys, and helps, in the smallest, downtown city parks, to make green oases in burning deserts of brick and stone pavements. But it is subject to the ravages of insect and fungous enemies to a greater extent than the oriental species.

THE GUM TREES

Southern people talk more about "gum trees" than people in the North.

Two of our three native species of Nyssa belong solely to southern swamps, and the third, which comes north to Canada, is oftener called by other names. All these trees are picturesque, with twiggy, contorted branches; tough, cross-grained wood; alternate, simple, leathery, but deciduous leaves, beautiful at all seasons; minute flowers and fleshy, berry-like fruits.

=The Sour, or Black, Gum=

_Nyssa sylvatica_, Marsh.

The sour or black gum of the South has a wide range, being hardy to southern Ontario and Maine. To the New Englander this is the "pepperidge"; the Indians called it "tupelo"; but the woodsman, North and South, calls it the gum tree, as a rule. "Black gum" refers to its dark gray, rough bark, which is broken into many-sided plates. By this, it is easily distinguished from the "red gum" or liquid amber, which grows in the same situations, but is not related to it. "Sour gum" refers to the acid, blue-black berries, one to three in a cl.u.s.ter, ripe in October.

We shall know this tree by its tall, slender trunk, clothed with short, ridged, full-twigged, horizontal branches. With no claim to symmetry, the black gum is a striking and picturesque figure in winter. It is beautiful in summer, covered with the dark polished leaves, two to four inches long. In autumn patches of red appear as the leaves begin to drop. This is the tupelo's signal that winter is coming. Soon the tree is a pillar of fire against yellowing ashes and hickories. The reds of the swamp maple and scarlet oak are brighter, but no tree has a richer color than this one. A spray brought in to decorate the mantelpiece lasts till Christmas holly displaces it. The leaves, being leathery, do not curl and dry, as do thin maple leaves, in the warm air of the house.

=The Cotton Gum=

_N. aquatica_, Marsh.

The cotton gum is draped in cottony white down as the new shoots start and the leaves unfold in spring. In midsummer this down persists in the leaf-linings, lightening the dark green of the tree-tops. The dark blue fruits of this species have no culinary value. The wood is used for crating material. The tree reaches its maximum height--one hundred feet--in the cypress swamps of Louisiana and Texas, its abundant, corky roots adapting it to its habitat.

=The Sweet Gum=

_Liquidamber styraciflua_, Linn.

The sweet gum is a tall tree with a straight trunk, four to five feet in diameter, with slender branches covered with corky bark thrown out in wing-like ridges. At first the head is regular and pyramidal, but in old age it becomes irregularly oblong and comparatively narrow. The bark is reddish brown, deeply furrowed between rough scaly plates, marked by hard, warty excrescences.

The leaves are lobed like a maple's, but more regularly, so as to form a five-pointed star. Brilliant green in summer, they become streaked with crimson and yellow. Wherever these gum trees grow, the autumn landscape is painted with the changeful splendor of the most gorgeous sunset. "The tree is not a flame, it is a _conflagration_!" Often along a country road the rail fence is hidden by an undergrowth of young gum trees. Their polished star leaves may pa.s.s from green into dull crimsons and then into lilacs and so to brown, or they may flame into scarlets and orange instead. Always, the foliage of the sweet gum falls before it loses its wonderful colors.

The flowers of the sweet gum are k.n.o.bby little bunches; the swinging b.a.l.l.s covered with curving horns contain the winged seeds, small but shaped like the key of the maple. One recognizes the gum tree in winter by these swinging seed-b.a.l.l.s, an inch in diameter, like the b.a.l.l.s of the b.u.t.tonwood, except that those are smooth. (_See ill.u.s.trations, pages 102-103._) The best distinguishing mark of sweet gums in winter are the corky ridges on the branches, and the star-shaped leaves under the trees. Sweet gum sap is resinous and fragrant. Chip through the bark, and an aromatic gum soon acc.u.mulates in the wound. The farther South one goes, the more copious is the exudation. In Mexico a Spanish explorer described, in 1651, "large trees that exude a gum like liquid amber." This is the "copalm balm"

gathered and shipped each year to Europe from New Orleans and from Mexican ports. The fragrant gum, _storax_ or _styrax_, derived from forests of the oriental sweet gum in Asia Minor, is used as incense in temples of various oriental religions. It blends with frankincense and myrrh in the censers of Greek and Roman Catholic churches. It is used in medicines also, and as a dry gum is the standard glove perfume in France.

Beautiful and interesting in every stage of growth, our native sweet gums are planted largely in the parks of Europe and are earning recognition at home, through the efforts of tree-lovers who would make the most of native species in ornamental planting.

The name, gum tree, is applied to our tupelos, and to the great tribe of Australian eucalyptus trees, now largely planted in the Southwest.

=The Osage Orange=

_Toxylon pomiferum_, Raff.

Related to figs and mulberries, but solitary in the genus _toxylon_, is the osage orange, a handsome round-headed tree, native of eastern North America, whose fleshy roots and milky, bitter, rubbery sap reveal its family connections with the tropical rubber plants. (_See ill.u.s.tration, page 119._) The fruits are great yellow-green globes, four to five inches in diameter, covered on the outside by crowded, one-seeded berries. This compound fruit reveals the tree's relationship to both figs and mulberries.