I learnt a new word today – thermogenesis. Not as you might imagine, what Adam and Eve wore under their fig leaves when it got a bit parky in Eden, but the surprising ability of some plants to generate their own heat.
Whilst enjoying the heartwarming sight of the first snowdrops yesterday, I remembered hearing somewhere that they generate heat at their tips which allows them to push their way up through snow.
So are snowdrops thermogenic? Despite a widespread belief that they are, I couldn’t find any evidence. Most thermogenic plants, which include the sacred lotus, seem to be on the large side and some, like the picturesquely named eastern skunk cabbage, smell a lot, neither of which seem to square with this petite and odourless late winter flower. One native plant that does display this behaviour is the cuckoo pint (Arum maculatum), which can, apparently, be 15° C warmer than the ambient temperature
And if snowdrops really do need heat to help them fight their way through the snow, wouldn’t it be better for them to be dark, so as to absorb heat, rather than white, which reflects it? A better hypothesis (for which I have no evidence) would be that their whiteness camouflages them against snow and reduces their chance of being eaten by birds. I’m not really sure how you would test this experimentally – maybe paint half the snowdrops red like the roses in Alice in Wonderland? Cutting edge science is harder than it looks.
Meanwhile, I shall be on the lookout for the first cuckoo-pint of spring.
Edvinas Stankunas, Plants that Generate Heat on http://www.technology.org/2014/07/24/plants-generate-heat/, accessed 13th Feb 2017 – this is a readable article that appears to be based on information derived from other, largely unreferenced, sources
Watling, J. R., Grant, N. M., Miller, R. E., & Robinson, S. A. (2008). Mechanisms of thermoregulation in plants. Plant Signaling & Behavior, 3(8), 595–597 – proper science, but a bit heavier going