Anatomic adaptation of stems of aquatic Utricularia species dragging turions to the bottom of their habitats

Turions are vegetative, dormant, overwintering storage organs formed in aquatic plants. We have observed that shoots with maturating turions of three robust aquatic Utricularia species possess an anatomical adaptation of the central cylinder in apical shoot segments. The senescent mother shoots drag turions in these species to the bottom of their habitat. This adaptation leads to impregnation of the central cylinder by substances preventing the stems from early decomposing. Using anatomical staining methods, we have aimed to elucidate the substances impregnating the central cylinder - partly lignin and mainly polyphenols.