Most thermogenic plants

Thermogenesis is the ability to generate heat among living organisms. Although a common feature to all warm-blooded animals, it is a relatively rare phenomenon among flora, currently known only in about 14 plant families. Pinpointing the most thermogenic plant species comes down to the criteria used to measure them. In terms of maximum rate of heat production across the whole flower/bloom, the titan arum (Amorphophallus titanum) of south-east Asia has been recorded generating a total of 34.53 Watts of energy; this is predominantly down to the fact that the titan arum is the world’s largest (unbranched) inflorescence. In terms of maximum rate of heat production relative to mass, meanwhile, the male florets of the arum lily Arum concinnatum (from the Aegean region) prevail, outputting as much as 0.43 Watts per gram at night. (By comparison, the spadix of the titan arum produces a mere 0.07 Watts per gram.) Based on the difference in ambient temperature and the flower, the most thermogenic plant is the eastern skunk cabbage (Symplocarpus foetidus) native to eastern North America – these wetland plants have demonstrated a differential of 25.6°C (78.1°F) in the field, and as much as 32°C (89.6°F) in a respirometry chamber.

All of the above figures were taken from a comparative paper by Professor Roger Seymour published in the journal Plant, Cell & Environment on 4 August 2010.

Many thermogenic plants seem to have evolved this self-heating power in order to attract pollinating insects, with the heat intensifying odorous chemicals, enabling them to draw pollinators from a greater range. Thermogenic plants also offer so-called “heat rewards” to invertebrates: warm sanctuaries to feed and seek mates that enable them to save energy that would otherwise be expended on heat production in cooler conditions.

Others, such as the eastern skunk cabbage, produce so much heat that they are able to melt through overlying snow in the early spring, providing them an evolutionary advantage by being able to bloom far earlier than many other plants.