Greg Belles, age 10, of Albany, New York, for his question:

How do they raise seedless oranges?

A naval orange has no seeds in its juicy sections. But sometimes there are a few inside the little round ball on one end of the fruit. You might think that these can be used to sprout more seedless orange trees. Not at a11. Seedless orange trees are produced by a man made miracle called grafting. So are other orange trees. The miracle works because the roots of one tree and the top of another tree can grow together. They merge to make a tree that is better than either of the parents.

The rootstock may be a bitter orange tree. Its fruit is poor but it resists diseases and hardships. The trunk of the young rootstock is cut down and grafted with a twig from a seedless orange tree. The clever grafting is cut so that special cells in the rootstock and the twig touch each other and grow together. In a few years, they grow to form a fine tree with sturdy roots and boughs filled with seedless oranges.