Prue did not seem to understand very well, so the Chief Gardener explained. "There are three kinds of plants," he said: "Annuals, biennials, and perennials. The annuals live but one season. They come from the seed each spring, and when they have grown and bloomed and made seed for another year they die. Sweet-pease and sunflowers and Davy's corn are annuals." "And radishes and beets," said Davy. "No, Davy. That is where you are mistaken." "But we have to plant them every spring," said Davy. "We do so to get good vegetables for our table. But if we were planting only for seed we would leave the roots in the ground, or take them up and reset them in the spring. Then they would send up long stalks to bloom and bear seed. Beets and radishes and turnips and most such things are biennials, which means that they bloom the second year and then die. They spend all the first year in laying up strength in the roots, to use in making seed the second summer. Some biennials, like the cabbage, lay up this strength in the thick stalk. The strength which they take up from the earth and from the air, through their leaves, they do not spend in flowers and show, but turn it into food for themselves, and the food is so good that men gather it for their own use." "I don't think that is quite right," said Prue, "after the poor thing has worked so hard all summer to be ready to bloom next year, for us to take it and eat it." The Chief Gardener smiled and shook his head. "I'm afraid we do not think much about the plant's rights," he said, "unless they happen to be the same as our own. And after all there are plenty of seeds saved every year--more than are ever planted." "And are potatoes biennials, too?" asked Davy. "No, potatoes are perennials. In the right climate they would live on year after year, laying up new strength each year for the next season's growth. Dahlias are perennials, too, and most of the grasses, and, of course, all trees, and shrubs. Your pinks, Prue, and sweet-williams, and the hollyhocks, are perennial, and live through the winter, though they bear a great deal of seed, which shows how determined they are to live on. These chrysanthemums also bear seed, and most plants have at least two ways, and some as many as four ways of producing others like them. Your onions, Davy, can be produced in four different ways. They can be grown from seed, from sets--which are little seed-onions taken out of the ground and kept through the winter--from bulblets--which are the little onions you saw growing on the top of the stalk last summer--and from multipliers--which are large bulbs broken into several small parts." [Illustration: THE SEED AND SETS OF THE ONION] "I should think an onion was surely perennial enough," said Davy, "with four ways of keeping alive." "Can you name the three kinds of plants now?" asked the Chief Gardener, turning to little Prue.