Kena Anne Eastman, age 9, of Costa Mesa, Calif., for her question:
HOW LONG DOES IT TAKE A PINE CONE TO BECOME A TREE?
If you thought the pine cone looks as if it might play an important part in the family life of the tree, you are right. The cone bears the seeds that produce more pine trees.
The seed producing process of the cone bearing trees, however, is very different from the seeding process of oaks, elms and most other trees. It is a long, patient job lasting through more than two years. And fallen pine cones finished their duties long ago.
The pine cones we find on the ground are old and dry, with their woody brown scales open and curved backward. The seeds they cradled were launched last fall or maybe several seasons ago.
Once in a while we find a fallen cone with its scales sealed shut. As a rule, this means that some mishap caused the cone to fall before its proper time.
When they fall, certain pine cones may be open only very slightly. But if they are in a healthy condition, their scales are certainly open to some degree. Rains and winter snows tend to warp their woody scales and through several seasons they open up wider.
The cone bearing cycle begins in the late winter, when an evergreen sprouts a new growth of twigs. The twigs bear the budding cones and each pine tree produces two different types of cones. Some are pollen cones that create the pollen that carries the sperm, or male seed cells. The others create the eggs or female seed cells. Later, the male and female cells merge to form fertilized seeds capable of growing into new pine trees.
The clusters of male and female cones are separated on different twigs. In the budding stage it is hard to tell which is which. But soon the male cones show signs of pollen and the female cones outgrow them.
In May or June, the grains of pollen are ready and so are the waiting egg cells. Both types of cone open their scales and the dusty pollen puffs among the trees in clouds of golden dust. Some of the drifting dust falls to the ground. But a few precious grains fall on the egg bearing cones, into the slightly opened scales.
After this event, the work of the small pollen cones is finished. They soon dry up and fall off the tree. The work of the seed cones is just beginning. They close up their scales and often seal them shut with weatherproof resin. This protects them through two summers and two winters. Through the first year, the pollen and egg cells develop separately inside the cones. At last the pollen grains are ready to grow long hollow tubes. The tiny sperm cells pass down to join the waiting female cells. The fertilized egg cells require another year or more to become seeds. Then the cones open for the second and last time, releasing the seeds on the breezes. Sometimes the deserted, open cones cling to the tree a long time, but finally they fall to the ground.
From start to finish, the seed bearing process takes the pine cones two or three years. The seeds are finally ready to emerge in late fall or early winter. Each sturdy seed bears its own wing. If the seed is lucky, it lands on suitable soil. Soon it sprouts roots and a tiny tuft of needles. in a few years it is a baby size tree.