In sheltered regions the seeds of trees may fall, sprout and take root close to their parent trees.  As a rule, the wind plays a prominent part in distributing seed in every section of the country.  Pine and fir seeds are equipped with wings like those of a bird or an airplane.  They enable the seeds to fly long distances on the wind before they drop to the ground and are covered with leaves.  Maple seeds fly by means of double-winged sails which carry them far afield before they settle.  Ash seeds have peculiar appendages which act like a skate-sail in transporting them to distant sections.  Cottonwood seeds have downy wings which aid their flight, while basswood seeds are distributed over the country by means of parachute-like wings.  The pods of the locust tree fall on the frozen ground or snow crust and are blown long distances from their source.  On the other hand, oak, hickory, and chestnut trees produce heavy seeds which generally remain where they fall.

Squirrels are the most industrious foresters in the animal world.  Each year they bury great quantities of tree seeds in hoards or caches hidden away in hollow logs or in the moss and leaves of the forest floor.  Birds also scatter tree seed here, there, and everywhere over the forests and the surrounding country.  Running streams and rivers carry seeds uninjured for many miles and finally deposit them in places where they sprout and grow into trees.  Many seeds are carried by the ocean currents to distant foreign shores.

The decay of leaves and woodland vegetation forms rich and fertile soils in the forests, in which conditions are favorable for the development of new tree growth.  When living tree seeds are exposed to proper amounts of moisture, warmth and air in a fertile soil, they will sprout and grow.  A root develops which pushes its way down into the soil, while the leaf-bud of the plant, which springs from the other end of the seed, works its way upward toward the light and air.  This leafy part of the seed finally forms the stem of the tree.  But trees may produce plenty of seed and yet fail to maintain their proper proportion in the forest.  This results because much of the seed is unsound.  Even where a satisfactory supply of sound fertile seed is produced, it does not follow that the trees of that variety will be maintained in the forest, as the seed supply may be scattered in unfavorable positions for germination.  Millions of little seedlings, however, start to grow in the forest each year, but only a small number survive and become large trees.  This is because so many of the seedlings are destroyed by forest fires, cattle and sheep grazing, unfavorable soil and weather conditions, and many other causes.

Beech and chestnut trees and others of the broad-leaved type reproduce by means of sprouts as well as by seed.  Generally, the young stumps of broad-leaved trees produce more sprouts than the stumps of older trees which have stood for some time.  Among the cone-bearing trees reproduction by sprouts is rare.  The redwood of California is one of the few exceptions.  The pitch pine of the Eastern States produces many sprouts, few of which live and develop into marketable timber.