Water Loving Trees - The Poplars
( Originally Published 1927 )
The poplars are plebeian trees, but they have a place to fill and they fill it with credit. They are the hardy, rude pioneers that go before and prepare the way for nobler trees. Let a fire sweep a path through the forest, and the poplar is likely to be the first tree to fill the breach. The trees produce abundant seed, very much like that of willows, and the wind sows it far and wide. The young trees love the sun, and serve as nurse trees to more valuable hardwoods and conifers, that must have shade until they become established. By the time the more valuable species are able to take care of themselves, the poplars have come to maturity and disappeared, for they are quick-growing, short-lived trees. The wind plays havoc with their brittle branches. Seldom has a good-sized poplar tree any claim to beauty.
Tenacity of life, if not of fibre, belongs to the poplar tribe. Twigs strike root and the roots send up suckers from underground; cutting off these suckers only encourages them to fresh activity. The only way to get rid of the young growth that springs up about an old tree is to use the grubbing-hoe thoroughly and patiently.
Poplar blossoms, borne in catkins, show the close relationship between this genus and the willows. The leaves, however, are always broad and leathery, and set on long stems. Twenty-five species are known, twelve of which are American.
The White Poplar Populus alba, Linn.
The white poplar is sometimes called the silver-leaved poplar because its dark, glossy leaves are lined with cottony nap. This sprightly contrast of light and shade in the foliage is most unusual, and very attractive in early spring; but the leaf-linings collect soot and dust, and this they carry to the end of the season—a fact which should not be forgotten by those considering the advisability of planting this tree in a city where much soft coal is burned.
The white bark of this European poplar reminds us of the birch family, though it has no silky fringe shedding from the surface. The leaves often imitate the maple in the divisions of their margins, justifying the name "maple-leaved poplar."
As a dooryard tree this species has a wider popularity than it deserves. The wind breaks the brittle branches, and when these accidents threaten its life, the tree sends up suckers which form a grove about the parent trunk, and defy all efforts to eradicate them, until the grubbing-hoe and axe have been resorted to.
The Lombardy poplar, a variety of the black poplar of Europe, is a familiar tree figure along roadsides, and often marks boundary lines between farms. Each tree is an exclamation point, its branches short and numerous, rising toward the zenith. The roundish leaves that twinkle on these aspiring branches make the tree pretty and interesting when young—just the thing to accent a group of round-headed trees in a park. But not many years are attained before the top becomes choked with the multitude of its branches. The tree cannot shed this dead wood and the beauty of its youth is departed. The trunk grows coarse, warty, and buttressed at the base. Suckers are thrown up from the roots. There is little left to challenge admiration. Since the tree gives practically no shade, we must believe that the first planters were attracted by its odd shape and its readiness to grow, rather than by any belief in its fitness for avenue and highway planting.
The Cottonwood P. deltoidea, Marsh.
The cottonwood justifies its existence, if ever a tree did. On our Western plains, where the watercourses are sluggish and few and often run dry in midsummer, few trees grow; and the settler and traveler is grateful for the cotton-woods. The pioneer on the Western prairie planted it for shade and for wind-breaks about his first home. Many of these trees attain great age and in protected situations are magnificent though unsymmetrical trees, shaking out each spring a new head of bright green, glossy foliage, each leaf responsive to the lightest breeze.
"Necklace-bearing poplar," it has been called, from the fact that children find pleasure in stringing for beads the green, half-grown pods containing the minute seeds. They also delight in gathering the long, red caterpillar-like catkins of the staminate flowers, the pollen bearers, from the sterile trees. A fertile tree is sometimes counted a nuisance in a dooryard because its pods set free a great mass of cotton that collects in window screens, to the annoyance of housewives. But this seed time is soon over.
Just these merits of quick growth, prettiness, and tenacity of life, belong to the Carolina Poplar, a variety of native cottonwood that lines the streets of the typical suburban tract opened near any American city. The leaves are large and shine with a varnish which protects them from dust and smoke. But the wind breaks the branches, destroys the symmetry of the tree's head, and in a few years the suburban community takes on a cheap and ugly look. The wise promoter will alternate slow-growing maples and elms with the poplars so that these permanent trees will be ready to take their places in a few years.
P. tremuloides, Michx.
The trembling aspen, or quaking asp, is the prettiest tree of all the poplar tribe. Its bark is gray and smooth, often greenish and nearly white. An aspen copse is one of the loveliest things in the spring landscape. In March the bare, angular limbs show green under their bark, one of the first prophecies of spring; then the buds cast their brown scales and fuzzy gray catkins are revealed. There are few shades of olive and rose, few textures of silk and velvet that are not duplicated as the catkins lengthen and dance like chenille fringe from every twig. With the flowers, the new leaves open; each blade limp, silky, as it unrolls, more like the finest white flannel than anything else. (See illustrations, pages 86-87.) Soon the leaves shed all of this hairy, protective coat, passing through various tones of pink and silver on their way to their lustrous, bright green maturity. Their stems are flattened in a plane at right angles with the blade. Being long and pliant besides, they catch the breeze on blade or stem, and so the foliage is never still on the quietest of summer days. "Popple" leaves twinkle and dance and catch the sunlight like ripples on the surface of a stream, while the foliage of oaks and other trees near by may be practically motionless.
The Balsam Poplar P. balsamifera, Linn.
The balsam poplar is the balm of Gilead of the early settlers, the Tacamahac of the Northern Indians. They squeezed the fragrant wax from the winter buds and used it to seal up the seams in their birch-bark canoes. The bees taught the Indian the uses of this glutinous secretion, which the tree used to seal the bud-scales and thus keep out water. When growth starts with the stirring of the sap, this wax softens; then the bees collect and store it against a day of need. Whether their homes be hollow trees or patent hives, weather-cracks are carefully sealed up with this water-proof gum, which the bee-keeper knows as "propolis."
Forests of balm of Gilead cover much of the vast British possessions north of the United States, and reach to the ultimate islands of the Aleutian group. They dip down into the states as far as Nebraska and Nevada. In cultivation, the species has proved itself a tree of excellent habit, easily propagated and transplanted, and of rapid growth. It has all the good points of the Carolina poplar and lacks its besetting sin of becoming so soon an unsightly cripple.
Narrow-leaved Cottonwood P. angustifolia, James.
Lance-leaved Cottonwood P. acuminata, Rydb.
Mexican Cottonwood P. Mexicana, Wesm.
These three cottonwoods line the banks of mountain streams at high elevations in the great system of mountain chains that stretch from British Columbia southward. The dancing foliage, bright green in summer, golden in autumn, lends a charming color note to the dun stretches of arid plain and the sombre green of pine forests. These trees furnish the settler fuel, shade, and wind-breaks while he is converting his "homestead" into a home.
Black Cottonwood P. trichocarpa, Hook.
Farther west, covering the mountain slopes from Alaska to Mexico, and liking even better the moist, rich low-lands, is the black cottonwood, the giant of the genus, reaching two hundred feet in height, and seven to eight feet in trunk diameter. Tall and stately, it lifts its broad rounded crown upon heavy upright limbs. In the Yosemite the dark, rich green of these poplar groves along the Merced River makes a rich, velvet margin, glorious when it turns to gold in autumn.
Swamp Cottonwood P. heterophylla, Linn.
The swamp cottonwood of the South has leaves of variable but distinctly poplar form, always large, broadly ovate, with slim round petioles. The white down of the unfolding leaves often persists into midsummer. On ac-count of the fluttering leaves the trees were called, by the early Acadians, " Langues de femmes"a mild calumny trace-able to the herbalist, Gerarde, who compares them to "women's tongues, which seldom cease wagging."
The wood of poplars, soft, weak, and of slight value for fuel or lumber, has within two decades come into a position of great economic importance. Wood pulp is made of it, and out of wood pulp a thousand articles, from toys to wheels of locomotives, are made. A state forester declared: "If I could replace the maples in the state forest by poplars today, I would do it gladly. It would be worth thousands of dollars to the state."