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Many plants (e.g. roses, palms) can be protected from frost during the winter if shielded with an appropriate coat that can be bought in garden shops. Do plants produce any heat that can be kept inside with these "clothes"?

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Some produce quite a lot, like Skunk Cabbage and the Voodoo Lily. The latter can even sustain temperatures over 15 degrees celsius above its surroundings. This is a fairly good article on exothermic plants –  Gordon Gustafson Feb 20 '12 at 22:29
    
The senator tree in Florida produced heat. It burned to the ground from internal combustion. –  J. Musser Mar 15 '12 at 13:19
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4 Answers 4

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Cellular respiration in plants is slightly different than in other eukaryotes because the electron transport chain contains an additional enzyme called Alternative Oxidase (AOX). AOX takes some electrons out of the pathway prematurely - basically the energy is used to generate heat instead of ATP.

The exact purpose of AOX in plants is still unclear. Plants will make more AOX in response to cold, wounding, and oxidative stress. We know of at least one plant (skunk cabbage) that exploits this pathway to generate enough heat to melt snow. This link gives a pretty good overview.

(AOX is dear to my heart, since my first 3 years working in a laboratory were spent studying this gene <3)

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This is interesting @Amy. Why do you say that the exact purpose of AOX is unclear? Do you mean it is unclear what AOX does, or it is unclear why it does it? –  Poshpaws Dec 22 '11 at 0:25
    
@Amy The melting snow part is really fascinating, +1 –  Rory M Dec 22 '11 at 11:19
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@poshpaws what AOX does is pretty well understood, but the "why" isn't completely clear. When the electron transport chain converts energy into heat, it's "lost" rather than doing something useful - making ATP. It may be because since plants can't run away from their problems (temperature, wounding from bugs, and other things that lead to reactive oxygen species) they need an additional way to deal with oxidative stress that other organisms never developed. –  Amy Jan 5 '12 at 1:03
    
I always thought the purpose of AOX (apart from heating) was as an electron sink to help decrease photoinhibition, in the same way that photorespiration is. –  Richard Smith May 24 '12 at 23:13
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Plants will be respiring continuously, which is an exothermic process. Therefore the plants will be producing a small amount of heat. The protection from frost may be more a result of the vastly smaller convection current of the coat compared to the atmosphere rather than by reducing any conduction away of heat produced by the plant, however.

Keeping the plant out of the wind by 'dressing it' will reduce the rate of transpiration when the stomata are open. I would very tentatively suggest that, as water has a very high specific heat capacity, having a greater volume of water within the plant would help to retain any heat that was produced by respiration. However this is entirely speculation on my part.

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Snow is also a good insulator, and these "coats" may mirror that effect. See here for some measurements of the temperature difference: snailstales.blogspot.com/2010/02/… –  Michael Kuhn Dec 19 '11 at 15:41
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"Snow is also a good insulator" - indeed, that's how igloos work. –  user132 Dec 19 '11 at 16:00
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Some plants have mitochondrial pathways that produce heat. That's why skunk cabbage can be seen poking outing of the snow in late winter/early spring. Here's a review: http://onlinelibrary.wiley.com/doi/10.1111/j.1744-7909.2010.01004.x/pdf

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These and other plants make use of the cyanide-resistant pathway. This is a short-cut in the electron transport chain that allows the plant to produce extra heat at the expense of not using those electrons to manufacture ATP. (It is called the cyanide-resistant pathway because it provides an alternate pathway for the electrons to take. Rather than killing the cell quickly via free-radical production, it is slowly starved via lack of ATP.) –  S. Albano Oct 11 '12 at 5:18
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Yes, respiration is exothermic and plants (like all living things) respire.

I think the effect of covering the plant has to more to do with reducing sensible heat loss , e.g. direct transfer of heat from plant to air) rather than latent heat loss (through evaporation).

The cover is effectively reducing the mixing of the air near the plant (and closer to the temperature of the surface of the earth) with the free atmosphere (closer to the temperature reported by the weatherman)

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