Catherine Edenfield, age 10, of Staten Island, New York, for her question:

What tree is used to make plywood?

Let's rate plywood high on the list of Greatest Inventions. The sturdy stuff does a multitude of jobs better than ordinary wood. Besides, it helps to stretch our dwindling supplies of trees and lumber. It is made from plies, or thin layers, of wood glued together in a tough sandwich. In ordinary lumber, the grain lines go in the same direction. In plywood, the layers are stacked so that one grain pattern goes up and down and the next one from side to side. This keeps the sandwich flat and makes it impossible to split.

Almost any kind of hardwood or softwood may be steamed and sliced to make plywood. Softwood may be steamed and sliced to make plywood. Softwood layers are cut from fragrant conifers ~   mostly Douglas fir and white fir, hemlock, redwood and ponderosa pine. The hardwood used may come from oak or birch, poplar or dozens of other tough trees. Often a plywood sandwich of ordinary woods has a top layer of handsome walnut or cherry, mahogany or some other glamorous wood from the tropics. This type is used for wall panels and fine cabinets.