Salicylic Acid Levels in Thermogenic and Non-Thermogenic Plants

The natural trigger for heat production in the thermogenic inflorescences of Sauromatum guttatum Schott (voodoo lily) was recently identified as salicylic acid (SA), which induced heat production at levels as low as 13 ng g f. wt−1. Since then the levels of SA were determined in other thermogenic and non-thermogenic plant species. In thermogenic inflorescences of five aroid species, and in male cones of at least four thermogenic cycads SA levels during heat production exceeded 1 μg g f. wt−1. SA was not detected in the thermogenic flowers of a water lily, Victoria regia Lindl. (Nymphaeaceae), and Bactris major Jacq. (Palmae). Levels of salicylic acid varied substantially in the floral parts of seven non-thermogenic species and in the leaves of 27 non-thermogenic species.