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Pressurized Ventilation in the Yellow Waterlily
Author(s) -
Dacey John W. H.
Publication year - 1981
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1937277
Subject(s) - atmosphere (unit) , transpiration , partial pressure , pressure gradient , environmental science , flow (mathematics) , transpiration stream , water vapor , vapour pressure of water , volumetric flow rate , ventilation (architecture) , current (fluid) , chemistry , ecology , atmospheric sciences , thermodynamics , mechanics , photosynthesis , biology , geology , physics , oxygen , biochemistry , organic chemistry
Current models of gas transport in aquatic plants hold that gases diffuse in an essentially static gas phase within the lacunae according to gradients in their individual partial pressures. This study introduces a new model of gases gas transport wherein the gases move through waterlilies in a mass flow. The internal gas spaces in Nuphar constitute a pressurized flow—through system, with ambient air entering the youngest emergent leaves against a small gradient in total gas pressure. This pressurization phenomenon is the result of purely physical processes driven by the gradients in temperature (thermal transpiration) and water vapor (hygrometric pressure) between the atmosphere and the lacunae of the youngest emergent leaves. The lacunae are continuous throughout the entire plant, and the older leaves vent the elevated pressure generated by the younger leaves. This arrangement gives rise to a flow—through pattern, accelerating both the rate of O 2 supply from the atmosphere to the roots, and the rate of CO 2 and CH 4 transport from the roots towards the atmosphere. This ventilation system represents an important adaptation by the waterlily to life in anaerobic sediments.