Yolanda Johnson, age 8, of Houston, tex., for her question:

Why do plants die in cold weather?

Most plants can stand the cold even when the temperature drops down below zero. But many of these plants and trees lose their leaves when the weather becomes freezing cold. They may seem to be dead, but actually they have just shed their greenery, and when warm weather returns their green buds will sprout again. Sometimes the tender buds of spring are nipped off by a late frost, but almost always they return.

Tender leaves are destroyed by frost because the cold air freezes their liquid sap to solid ice. The sharp spikes of ice crack and split the delicate veins of the green leaves. The ice melts when the weather warms up, but the fragile leaves are shattered. They wither away, turn black and soon fall off the trees and plants.