HOW BIG TREES GROW 43 
about forty years old. Some trees may bear seed at 
from six to ten years of age but very often such seed 
fails to germinate. 
Mother Nature seems extremely anxious to have tree 
species distributed as widely as soil and climate will 
permit and so we find various devices to secure the scat- 
tering of seeds. 
Willow and poplar seeds are attached to a fleck of 
down, and may be carried long distances by the wind. 
Ash, maple and tulip trees have seeds with long wings 
which cause them to whirl in the air as they fall, 
greatly increasing the distance they may be carried by 
the wind. Some seeds like chokecherry or red cedar 
have a fleshy coat which is eaten by the birds who thus 
carry the stone or seed proper long distances. Still 
other trees, like chestnut, hickory and walnut, are 
largely distributed by squirrels since the nuts are too 
heavy to be carried by the wind and will roll or bound 
only short distances from the tree. 
Most of the evergreens have winged seeds borne on 
the inside of the cone scales and in spite of their com- 
paratively small wings they can be carried long dis- 
tances in the autumn winds. An island lying one-half 
mile from the nearest shore of an Adirondack lake 
was completely burned over some years ago. All the 
trees were killed, the shrubs were consumed and the 
litter was burned down to the mineral soil thus de- 
stroying any seed which had previously fallen. Never- 
theless within a few years a splendid stand of spruce 
seedlings was started from seed trees on the shore, the 
winged seed having been blown out to the island by 
the strong wind. 
Seed in favorable years is produced im enormous 
quantities but a large portion of it never germinates. 
