Thousands of tree seeds are sown where but tens may hope to germinate and grow. Some seeds (e. g., willow) must germinate at once or they lose their vitality and die. Most of these cannot start unless they fall in very moist soil. So each has its peculiar limitations, and these keep the number of seedlings down. Fortu nate kinds are not particular as to soil. This is especially true of those whose seeds will wait till a second year if the first does not offer them a chance to grow.
The willows illustrate better than other trees another method of reproduction. They rise superior to the limitations of their feeble seeds, and cast off twigs which strike root and grow into trees. Many willows have twigs that are brittle at the base. Touch one lightly and off it snaps in your hand. Every wind breaks off these natural willow cuttings and scatters them. Stream banks are lined for miles with trees of one kind. The twigs floating down stream lodged and grew. Sandbanks are covered by the same means. Even willow posts set green follow the twig habit and grow into trees. Osage orange and mulberry, poplar and basswood root quickly as cuttings. Theoretically, any plant will do the same. In practice, few trees are economically propagated in this way.
Young chestnut and oak trees follow old ones by the sprouting of the old stumps. It is not uncommon to find an ancient stump with a whorl of young trees circling its base—from five to a dozen of them. Foresters call this the coppice method of renewing woodlands. It is a cheap way to reproduce timber. These
"suckers" grow rapidly, for they have the whole root system of the parent tree to feed them. Such trees, however, are short lived. Most of the familiar hardwoods sprout from the stump — maples, elms, beech, ashes and locusts. Also the softer-wooded birches, basswoods, willows and poplars. The only conifers that do this are the redwood and the pitch pine.
It is common to see a white poplar or a Lombardy poplar or a garden plum tree growing neglected in the midst of a crowd of youngsters. These are not seedling trees, but suckers from the parent roots. They resemble coppice growth where they spring out close to the tree's "collar," but they have not waited for the removal of the old trunks. Such trees are nuisances on a lawn or in a fence row. However, they illustrate more of the methods that trees resort to to insure the perpetuation of their kind. In the race for life the trees with these secondary means of propagation, reinforcing the seed, are winners. Con sider, for instance, the pines. The one species in the East which comes up from the stump is the pitch pine. It rises like the Phoenix, from devastating fires, and after the sawmill has de parted, when other species must rely on seeds alone. The result is marked. Though not the most valuable Eastern pine, it is the one best able to hold its own in the race for life.
By seeds, by sprouts and by cast-off twigs the forest has ever renewed its youth and extended its boundaries. By these means it has resisted the forces which work toward its extermina tion.