Leaf dimorphism in aquatic angiosperms: significance of turgor pressure and cell expansion.

Depending on environmental conditions, the aquatic angiosperm Callitriche heterophylia can develop two different leaf types with distinctive morphological characteristics. Cellular turgor pressure seems to act as the biophysical mechanism responsible for the selection of leaf form in control conditions designed to mimic the natural habitat of this plant. The experimental induction of leaf form involves the ability of various treatments to mediate cell expansion through their effects on turgor pressure or wall extensibility.