BLACK COTTONWOOD
(Populus Trichocarpa)
This member of the cottonwood group is a strong tree that holds its ground in various latitudes and at many elevations, ranging from sea level up to eight or nine thousand feet, and in latitude from Alaska to southern California, a distance of nearly three thousand miles. Its east and west extension is more restricted and seldom exceeds four hundred miles. Its habitat covers an area of half a million square miles, and in that space it finds conditions which vary so greatly that the tree which can meet them must possess remarkable powers of adaptation.
Beginning in Alaska and the interior of Yukon territory, it has an arctic climate. It there not only grows on the coast, but it strikes the interior. It appears on the headwaters of several streams which flow into the Mackenzie or Hudson bay. It passes south through British Columbia and enters the United States west of the Rocky Mountains. It has been reported as far east as Idaho and Montana, but further information is needed before its limits in that direction can be definitely fixed.
When it enters California it prefers the elevated valleys and canyons of the Sierra Nevadas, though it occurs sparingly among the coast ranges. It is generally found in the Sierras at elevations of from 3,000 to 6,000 feet, though it occurs between 8,000 and 9,000. Among the San Jacinto mountains of southern California it grows at an altitude of 6,000 feet.
When it occurs at low levels it is usually found on river bottoms and sand bars, in sandy and humous soils, and there the largest trees are found. At higher elevations it is more apt to occur in canyon bottoms and gulches, in moist, sandy or gravelly soil, and in such situations the black cottonwood is smaller. The best growth occurs where the climate is humid and the precipitation is great. Beyond the reach of sea fogs, where the tree depends on soil moisture chiefly, it is smaller.
It is an intolerant tree. It must have light. When it is crowded a tall, slender trunk is developed and the small crown is lifted clear above its competitors into the full light. If it cannot succeed in gaining that position its growth is stunted or the tree meets an early death.
The black cottonwood is the greatest of the cottonwoods. This country produces no other to match it, and, as far as known, the whole world has none. The Pacific coast is remarkable for the giant trees it produces, but most of them are softwoods—the redwoods, the bigtree, the sugar pine, Douglas fir, western larch, noble fir, Sitka spruce and western red cedar. This cottonwood is the largest of the Pacific coast hardwoods. In trunk diameter it is excelled by the weeping oak in the interior valleys of California, but when both height and diameter are considered, the black cottonwood is in the West what yellow poplar is in the East, the largest of the hardwoods.
Sargent says this tree reaches a height of two hundred feet and a diameter of eight, but Sudworth is more conservative and places the trunk limit at six feet. The average size is much below the figures given, but abundance of logs exceeding three feet in diameter reach the sawmills of Washington and Oregon.
Old trees range from 150 to 200 years in age, but trees under 100 years old are large enough for saw timber. Records of the ages of the largest trunks have not been reported.
Black cottonwood is a prolific seeder, but the seeds do not long retain their vitality. If they find lodgment in damp situations, where other conditions are favorable, the rate of germination is high. Seedlings are often very numerous on wet bars.
The excellent quality of the wood and its suitability for many purposes bring it much demand on the Pacific coast. In the state of Washington more than 30,000,000 feet were used by wood-using industries in 1910. Smaller quantities were reported in Oregon and California.
In strength the wood is approximately the same as common cottonwood, but in stiffness it much exceeds the eastern species. Its elasticity rates high, and compares favorably with some of the valuable eastern hardwoods. In weight it is slightly under common cottonwood. Trees are of fine form, nearly always straight, and are generally free from limbs to a considerable height.
The wood is grayish-white, soft, tough, odorless, tasteless, long-fibered, nails well, is easily glued, and cuts into excellent rotary veneer with comparatively small expenditure of power. It does not split easily after it has undergone seasoning, and this property commends it to box makers. It is little disposed to shrink and swell in atmospheric changes. The absence of odor and taste gives it much of its value for box making, because foods are not contaminated by contact with it.
It is manufactured into veneer berry baskets and is one of the most suitable woods on the Pacific coast for that purpose. Candy barrel makers use it in preference to most others, and a long line of woodenware articles draw much of their material from this source. Many thousands of cords are cut yearly for the pulp mills, where material for paper is produced. Black cottonwood and white fir are the principal woods used for pulp on the Pacific coast.
Not only is it used for rotary-cut veneer, but it is made into cores or backing on which veneers of costly woods are glued in the manufacture of furniture, interior finish and fixtures for banks, stores and offices. It serves in the same way in casket making, and is demanded in millions of feet.
It is employed in amounts larger than any other wood by excelsior mills in the northern Pacific coast region. It is the only wood demanded by that industry in Washington and 6,400,000 feet were cut into that product in 1910.
Slack coopers find it as valuable in their business in the far West as the common cottonwood is in the East, and hundreds of thousands of staves are made yearly. It is in demand for the manufacture of flour barrels and those intended for other food products.
Trunk makers use it in three-ply veneers for the bodies, trays, boxes and compartments of trunks and for suit cases. Though soft and light, it is very tough, and sheets of veneer with the grains placed transversely resist strains much better than solid wood of the same thickness.
Vehicle makers employ black cottonwood for the tops and shelves of business wagons. Another of its uses is as bottoms of drawers for bureaus, wardrobes, and chiffoniers, and as partitions in desk compartments. A full line of kitchen and pantry furniture is made wholly or in part of this wood in the regions where it is cheap and abundant.
The cottonwoods belong to a very ancient race of broadleaf trees, and like several others, they seem to have had their origin, or at least a very early home, in the far North, where intense cold now excludes almost every form of vegetable growth except the lowest orders. The Cretaceous age saw cottonwoods growing in Greenland. The cotton which then, as now, carried the seeds and planted them fell on more hospitable shores then than can now be found in the far frozen North. The genus was not confined to the arctic and subarctic regions, however, for there were cottonwoods at that time, or later, in more southern latitudes. There were many species in the central portion of this country, and also in Europe, long before the ice age destroyed all the forests north of the Ohio and the Missouri rivers. Some of the old species long ago ceased to exist, but others appear to have come down to the present time without great change.
The cottonwood shows wonderful vitality, which is doubtless a survival of the characteristic which enabled it to come down from former geologic epochs to the present time. A damaged and mutilated tree will recover. A broken limb, thrust in the ground, will grow.
Black Poplar (Populus nigra) is quite distinct from black cottonwood, though both belong to the same family. The latter is a Pacific coast species, while the former belongs in Europe, although it may have been introduced into that country from Persia or some other eastern region. It is common in the United States, on account of having escaped from cultivation. The best known variety of this tree is the Lombardy poplar (Populus nigra italica). It is easily recognized by the characteristic attitude of the branches which grow upward close against the trunk. The crowns of the trees are very long and slender, sometimes not ten feet across though fifty feet high. Their slimness gives the trees the appearance of being much taller than they really are. They were formerly popular for planting along lanes and in door yards. Their slender and pointed spires cut the horizon with a peculiar effect. Planting is less common now than formerly, because people have come to know the trees better. They are probably the most limby of all the members of the cottonwood group. The long trunks are masses of knots when the limbs have been trimmed away, and any desire to make lumber of the trees is apt to be discouraged, though not infrequently logs go to local sawmills, and farmers haul the boards home to put them to some use about the place. In Michigan and Ohio, box makers use the lumber for the rougher and cheaper articles which they turn out.
The most discouraging thing about Lombardy poplar is the tendency of the trees to send up sprouts. The living trees do it, and the stumps are worse. The sprouts are not confined to the ground immediately round the base of the tree, but spring up many feet or many yards distant, until they produce a veritable jungle. Years are often required to complete their extermination by grubbing and cutting.
White Poplar (Populus alba) is a European species but has become naturalized in the United States. It is widely planted as a shade tree, and has escaped from cultivation. It may be known by the white undersides of its small leaves, and by its yellowish-green bark which remains smooth, except on large trunks. It is not yet important as a source of lumber, but the vigor of its growth indicates that it may sometime become so. The wood is soft, white, and light. Some persons consider the tree objectionable as an ornament because of its habit of sending up sprouts from the roots, and because its woolly leaves collect dust and smoke until they are almost black by the end of summer.
Black cottonwood branch
