Most crop and horticultural plants are seriously injured or even killed if the soil in which they are growing is flooded with water for an extended period of time. It generally is assumed that flooding is equally injurious to most species of forest trees and limits the natural distribution of many species to relatively well drained sites. It is supposed, for example, that pond pine occupies wet sites in the Atlantic Coastal Plain because its roots can survive flooding and the accompanying poor aeration better than the roots of loblolly pine or shortleaf pine. This view was not supported by the results of an experiment by Gaiser (1) who studied the effects of flooding on loblolly pine and pond pine seedlings grown in the greenhouse. The seedlings were planted in 5-quart oil cans filled with sandy soil. Holes were punched in the bottom of the cans and a layer of gravel was placed beneath the soil to facilitate drainage of the soil. Various periods of flooding, alternating with periods during which the soil was drained, were maintained for three months in the spring of 1948. The loblolly pine seedlings appeared to be more resistant to flooding injury than pond pine seedlings, and both species made better growth in soil intermittently flooded for short periods (two days out of nine) than in soil maintained at field capacity or lower. These results were so unexpected that a more extensive experiment was planned to study the effects of flooding.