Q: How did carnivorous plants evolve?


Pinguicula gypsicola


Utricularia purpurea A: The evolution of carnivorous plants is not well known. This is not because there is anything really mysterious going on, it is just that carnivorous plants do not have very rigid parts which are likely to get fossilized, nor do they make huge numbers of leaves each season to increase the chance of one being fossilized. I have no doubt there are great fossils of carnivorous plants someplace, but we just have not yet found them.

There are some exceptions to this. For example, if you read the relevent entry on the carnivorous plant Aldrovanda vesiculosa, you will see I mention that there is a good fossil record for this plant and its progenitors. Unfortunately, the record is of the seeds. Only one fossil leaf of this plant's ancestors has ever been found.

Several now-extinct species of plants, described from fossil pollen, have been placed in the genus Fischeripollis, in the Droseraceae (i.e., the sundew family). The currently described species include F. halensis from central Australia, and F. krutschei and F. undulatus from Europe. At least one other species awaits publication.

More recently, a fossil of a plant that looks a great deal like an ancestor of Sarracenia or Heliamphora has been discovered, and named Archaeamphora longicervia. Check out the photo in Li (2005), or in my book. The fossil is really amazing.

Also, a fossil of something that looks like an ancestor of Byblis has also been discovered, and a few leaves of Roridula have been found in amber.

In spite of our lack of direct much evidence, we can still infer a few things about carnivorous plant evolution. First, all known carnivorous plants are angiosperms (flowering plants), so they could not have evolved more than 60-125 million years ago. Second, they must have evolved after insects had evolved which were associated with plants as pollinators or at least foragers. Third, they have evolved several times, since many of the carnivorous plants arose from unrelated plant families. (For a bit more on this, consider the clades I discuss here.) Fourth, a great deal about the evolution of plants can be inferred by studying genetic relationships among them. For example, a detailed paper on carnivorous plant relationships that you should read--if you are interested in this stuff--is Schlauer 2010.


Arctostaphyllos bark I want you to understand that there is a constant interplay between plants and animals. Much of it goes without notice. For example, the common western (noncarnivorous!) shrub manzanita (Arctostaphyllos spp.) has funny peeling park to prevent pests from gaining a foothold in its tissues. The eggs and larval bugs tend to get knocked off before they can cause damage. Stuff like this is happening all the time. It's a tough world out there for bugs, plants, and everything else.

While carnivorous plants surely are interesting, they still engage in all the same processes that conventional plants do, like photosynthesis. It is quite clear they are part of the normal plant world on the Earth, but they have evolved a few noteworthy tricks. Do not get confused into thinking they did not evolve on this planet!

(If you think that my previous paragraph is weird. You should read my e-mail. Some people think that carnivorous plants must be aliens from other planets. I wish I were joking.)

Page citations: Degreef, J.D. 1997; Juniper, et. al. 1989; Li, H. 2005; Macphail, M.K., & Truswell, E.M. 2003; Raven, et al. 1981; Sadowski, E-M. et al. 2014; Schlauer, J. 1997, 2010; Truswell, E.M., & Marchant, N.G. 1986; reader contributions; personal observations.