Carnivorous plants, which trap insects and other small animals in diverse ways, are found around the world today. But until recently, their only known fossils were seeds of one aquatic species, Aldrovanda. German researchers have made the first discovery of a plant’s fossilized insect-trapping parts: two tiny leaves (5 and 4.5 mm long) believed to be in the genus Roridula, encased in Baltic amber from a coastal Russian mine.
Modern Roridula trap insects with sticky tentacles along their leaves. Unlike many carnivorous plants, they do not digest their prey directly; it is eaten by two beetle species which live on them and nowhere else. The plants absorb nutrients from the beetles’ droppings, and are considered carnivorous because they are nourished by their trapped prey.
The preserved leaves have many similarities with modern Roridula, including tentacles of five lengths with specialized roles in catching and holding prey, distinctive patterns of tentacles, microscopic glass-clear hairs, and a pore at each tentacle’s tip. Detritus on the tentacles indicates stickiness. They lived 35-47 million years ago (Eocene Epoch), when the area was much warmer and forested, with the nutrient-poor soil in which carnivorous plants are adapted to thrive.
The fossil’s location is striking. Roridula now live only in South Africa, and the genus was long believed endemic to the southern hemisphere. This discovery in Russia indicates that it was once far more widespread, changing our perceptions of its evolution.