Water transport at the extreme - Restoring the hydraulic system in a resurrection plant

It is a reasonable assumption that particular features of the water transport process might be emphasized and especially conspicuous under extreme conditions. For example, in investigating how the plant deals with the need to lift water against gravity one would study tall trees (Zimmermann et al., 1993). The processes by which roots acquire water from their surroundings might be expected to be especially obvious in mangroves rooted in sea water (Zimmermann et al., 1994). The forces responsible for driving water through the xylem should be most easily found at times of peak transpiration (Canny, 1997). Thus, in the present studies, the mechanisms responsible for removing gas from vessels and replacing it with water were investigated in Myrothamnus when nearly all the water had been removed and the gas content was a maximum if the force is indeed 'root pressure', then one mysterious process has been explained in terms of another.