Thermogenesis, as it occurs in the plant inflorescence has been observed and studied for over two centuries. At least seven thermogenic families of plants are known including Annonaceae, Araceae, Arecaceae, Aristolochiaceae, Cycadaceae, Cyclanthaceae, and Nymphaeaceae. The sequence of thermogenic events is very precise and highly synchronized in each species. The physiology is not well understood, but the recent identification of salicylic acid as the triggering hormone for thermogenesis has opened the door for further research, especially in the areas of plant signal transduction pathways and systemically acquired resistances. Thermogenesis has proven to be an advantageous process to plants for maximizing pollination and limiting hybridization. Beetle pollinators also benefit from the phenomenon.