Most trees will immediately slow or stop growth under flooded conditions. Old myths suggest trees grow larger in diameter when flooded. A diameter increase can occur in some species caused by bark and wood tissues producing more spaces between cells, and producing larger cells with thinner walls. This low density tree tissue around the outside of a tree can represent a large diameter growth spurt. In some trees, this growth pattern may be a prelude to final rapid decline and death.
Flooding can also initiate many adventitious roots on the submerged stem area and large roots.
The more flood tolerant the species, the more likely the species will form adventitious roots. Adventitious roots increase the capacity of the tree to uptake materials, oxygenate the rhizosphere, detoxify soil materials, and increase root growth regulators. Young trees can also be buried by sediment, pushed over, or swept away. Major damage can occur along the young stem and root collar area that may haunt the tree through the rest of its life. Soil fill requires a quick root response to new soil conditions.