Ricky Narvett, age 10, of Mundelein, Illinois, for his question:

Where do they get seeds to crow seedless oranges?

The world's first oranges grew on wild trees, with nobody to tend them. They were no bigger than little plums and they tasted quite bitter. Their seeds fell to the ground and grew into more wild orange trees. In time, people chose the trees that grew the best wild oranges and tended them in their gardens. Then they learned about grafting.

A grafted tree is a two in one. The root belongs to a sturdy tree that can grow in the wild, but its fruit is rather small and bitter. The top grafted onto its trunk came from a tree that bears large tasty fruit. But the root of this tree was rather fragile. Seedless oranges come from grafted trees. A few have seeds, but trees from these seeds would not grow big juicy oranges. So twigs from the seedless orange boughs are grafted onto the rooted stems of more sturdy trees.