Supercooling along an Altitudinal Gradient inEspeletia schultzii, a Caulescent Giant Rosette Species

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Abstract
Rada, F., Goldstein, G., Azocar, A. and Torres, F. 1987. Supercooling along an altitudinal gradient in Espeletia schultzii, a caulescent giant rosette species.—J. exp. Bot. 38: 491–497. Tropical high Andes plants may be exposed to sub-zero temperatures any night of the year. These plants have to rely on mechanisms which protect them from these environmental conditions but at the same time allow their growth and development. Supercooling has been found to be the principal avoidance mechanism in leaves of the caulescent giant rosette genus Espeletia in the Andes. We report here the differences in supercooling capacity and cold injury in several Espeletia schultzii populations growing along an altitudinal gradient. The relationships between supercooling, water potential and leaf anatomy were also investigated. The supercooling capacity increased and injury temperature decreased from lower to higher elevation populations. These changes may be explained in terms of physiological, morphological and anatomical characteristics of the leaves.