Many animals are warm-blooded, meaning they keep their body temperature reasonably constant despite fluctuating ambient temperatures.

When it gets cold, they turn on the heating, so to speak.

Many animals can do this - but by no means all.

Even among the terrestrial vertebrates, a number are cold-blooded, namely most of today's reptiles.

In fact, warm-bloodedness evolved independently at least twice in vertebrate evolution: in mammals and in the common ancestors of pterosaurs and dinosaurs, the latter giving rise to distinctly warm-blooded birds.

Ulf von Rauchhaupt

Editor in the “Science” section of the Frankfurter Allgemeine Sunday newspaper.

  • Follow I follow

The question arises as to whether there are also plants that can heat themselves up.

And indeed, there is.

This so-called thermogenesis is secured in at least nine flowering plant families.

However, they are often very peculiar plants, almost bizarre for our notions of plant life, which are trained in the flora of temperate Central European zones.

There is, for example, the giant water lily

Victoria amazonica

native to the Amazon region .

Its flower is as big as a child's head and is brilliant white on the first of the two evenings it blooms.

And when it opens towards sunset, it gets warm.

This is said to be noticeable even with a hand held over it, but it was also systematically measured in a study published in 2006 in the

Annals of Botany

on the Rupununi River in Guyana: it got up to 34.7 degrees Celsius in the water lily blossoms, at most 25.2 degrees ambient temperature.

But the plant doesn't do that because the tropical evenings on Rupununi are too cold for it.

Rather, it attracts beetles of the species

Cyclocephala hardyi

.

These scarabs love warmth, but can only produce it themselves with great effort and are now compensated by the water lily for their pollination services with a luxurious overnight stay: The beetles stay inside the muffled warm glory until the following evening, where they mate and feed on flower products make amends.

The next evening, when the water lily opens a second time, the beetles come out again to celebrate the next party

in another

V. amazonica flower.

A whole lot less appetizing – at least for the human sensory system – is the case with a number of thermogenic species from the aroid family, where the ability to heat up is particularly common and particularly pronounced.

Names like stink cabbage a.k.a. Eastern Skunk Cabbage (

Symplocarpus foetidus

), Dead Horse Arum Lily (

Helicodiceros muscivorus

), or Voodoo Lily (

Sauromatum venosum

) hint at what's involved: their flowers emit an odor of excrement or rotting flesh to attract suitably oriented insects .

The strong aromas seem to require elevated temperatures for their secretion, because odor and heat development are often observed together.

However, not all thermogenic aroids tend to have an unpleasant odor.

Philodendron bipinnatifidum

, for example, is a popular houseplant and its flower can reach temperatures of up to 45 degrees in its Amazonian homeland.

The heat output of the stinky cabbage S. foetidus

, which is native to North America, is also record-breaking

.

Its flower warms up to 35 degrees above the ambient temperature.

This allows the early bloomer to easily melt away obstructive snow cover.

However, since most thermogenic plants are native to the tropics, this defrosting function may only be an evolutionary side effect.