VENTILATION BY FLOATING LEAVES IN NUPHAR

Abstract

The network of internal gas spaces in the yellow waterlily constitutes a pressurized flow‐through system which forces oxygen to the rhizome buried in anaerobic sediment. This ventilation has been documented previously in a subspecies of Nuphar luteum with aerial leaves, and appeared to occur only during daylight when the leaves are warmed by the sun's radiation. In this study we have found the ventilation system operating in two different subspecies of N. luteum growing in Alaska and in Massachusetts. These plants have floating leaves so that during certain times of the year the leaves are warmed not only by the sun in daylight but also by lake water at night, allowing the ventilation to continue during darkness.