Back to early May again, when the elm trees are green with their fruit clusters, before the leaves are fully out. Elm trees grow scattered through the woods, and no wonder: the seeds have papery rims, and the wind catches these little falling discs, and scatters them far from the tree where they were born.
The ailanthus tree, whose long, fern-like leaves make it look like a tree from the Tropics, is sowing its seeds all winter, with the help of the wind. Examine one. In the middle of a slim blade is the little seed. The blade is twisted as it ripens, and it sails through the air with a tilting, uncertain flight. After a look at a bunch of these seeds, and after throwing a handful of them out of an upper window, and watching them as they sail away, we shall understand how it is that ailanthus trees spring up in most unexpected places, year after year. And we shall bless the breeze that plants such trees along the hot pavements, and in the ugly back alleys of towns and cities, where few trees are able to grow at all.
TREE SEEDS THAT HAVE PARACHUTES
It is a thrilling moment when the man who goes up with the balloon lets go at last, and drops to the ground. Before he drops, an umbrella-like parachute opens, and by its aid, he comes to the ground gracefully, slowly, and alights unhurt. Should anything go wrong with his parachute he would drop to his death, so every onlooker is anxious as he comes down, and breathes a sigh of relief when the wonderful feat is accomplished.
Seeds with wings sail away on the wind, and seeds with parachutes descend so slowly and gracefully that the winds carry them far out of their courses. The trees most fortunate in scattering their seeds, and thus colonising new territory, have peculiar devices.
The seeds of the basswood hang in clusters attached to a narrow, leaf-like blade. This is a parachute, by which the whole cluster is able to sail away on a good breeze. There is no seed parachute like this among our forest trees. By this sign alone we may know the basswood trees.
The balls of the sycamore bump against the branches, and tiny seeds with hairy parachutes are loosened and scattered. Each is a minute spike, which might drop to the ground, but for the umbrella-like parachute made of a brush of fine hairs. By this, the wind lifts the seed, and carries it away.
Willow seeds, and those of the poplar, are almost too small to be seen. Each seed is hid in a dainty fluff of white cotton, and in this the seed rides. We may miss seeing these trees in fruit, unless we look at the down which accumulates in June on the screens of windows and doors. The air is full of the fluffy stuff when the pods open. In a few days this harvest is over, and we may find the empty pods on the ground under our neighbour poplars, cottonwoods, and willows.
The blue beech, or hornbeam, has a parachute which is leafy, and crinkled so as to look almost like a little boat. The shiny seed sits in one end, and when it gets free, it has a fine long sail through the air before it settles to the earth.
There are wings and parachutes on the seeds of other trees. When you find them you may know that the wind is the partner of the tree, by robbing it of its children. The wind is saving those children from death, which would have been their fate, if they fell on the ground under the shadow of the parent tree. If all the fields that adjoin the woods were left uncultivated for a few years they would grow up to forests. We know the name of the sower, who gathers seeds in the woods, and plants them; who is busy all the year at the endless work of the harvest and the sowing.