Effects of Depth of Flooding on Growth and Anatomy of Stems and Knee Roots of Taxodium Distichum

Abstract

Depth of flooding of Taxodium distichum trees influeneedin height and diametergrowth, formation of knee roots , and anatomy of sterns and knee roots. Height growth was progressively redueed and diameter growth was inereased as the level of the flood water was inereased. Formation of knee roots deereased as the depth of flooding inereased. Traeheids in the submerged portions of sterns of deeply flooded trees were shorter, slightly wider, and had thinner walls than traeheids of shallowly flooded trees. The inner bark of the submerged sterns of deeply flooded trees had wider phloemrays and more intercellular space than the bark of shallowly flooded trees. The xylem anatomy of knee roots resembled that of the xylem in the submerged portions of sterns of deeply flooded trees. Flooding stimulated ethylene produetion by stern bark and apieal portions of knee roots. An interaetive role of ethylene and auxin in anatomical responses of Taxodium to the flooding is postulated.