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Ancient Carnivorous Leaves Found in Amber

plant in amber

Image credit: Fossil leaf of a flypaper trap plant in Baltic amber / Alexander R. Schmidt, University of Göttingen

When studying Baltic amber date back from the Eocene epoch, scientists have found the first fossilized carnivorous plant traps so far. Coming from insect-eating flowering plants, such leaves are as old as 35 to 47 million years, possibly belonging to the same family of a South African flypaper trap plant. The latest findings have been released in the recent edition of Proceedings of the National Academy of Sciences.

Fossil tree resin, or namely amber is capable of well- preserving microscopic details of small organisms, but it is rare to find fossils to be enclosed in amber everywhere else. In comparison of insects and other animals, plants are unusually trapped this way. However, seeds from the aquatic carnivorous plant called Aldrovanda, are an exception, because they are still floating in some continents now. Previously there was no report in the fossil record about carnivorous plant traps yet.

At present, Alexander Schmidt from the University of Göttingen in Germany and his international team have found  two carnivorous leaf fossils which are enclosed in a piece of Baltic amber collected from a mine near Kaliningrad, Russia some time ago. These two leaf fossils have kind of properties similar to Roridula, an adhesive flypaper trap plant discovered just in the southwestern cape of South Africa. These plants own sticky, resinous trapping glue as well as tentacles of different size, which are organized in a hierarchical way. The function of the longest tentacles is involved in making the first contact with the prey. When the medium-sized tentacles are able to stick to it, the smallest tentacles would immobilize the prey in the end.

It is known that modern Roridula have unique capability compared with other carnivorous plants. Living in a complecated mutualistic association, they are dependent on symbiotic insects in regard to digesting and obtaining nutrition from entrapped prey. As a matter of fact, two resident species of “Roridula bugs” eat the trapped animals as their food, and then the plants make sure that their nutritional uptake would come from the bugs’ feces. In Schmidt’s description, it was unexpected to discover such leaves in the European fossil record, because Roridula is usually constrained to South Africa.

Measuring five millimeters long and 0.2 millimeters wide at the base, these new fossil leaves look like modern Roridula species, because they are strewn with unicellular hairs and multicellular stalked glands (or tentacles) with a pore at the apex. With five tentacles of different size the fossil leaves are found to have the apex of each narrow, tapered leaf which ends in a single tentacle. In addition, scientist also discovered the adhered organic remains that clearly show in which way that the plants released kind of sticky secretion exactly same to the adhesion traps of carnivorous plants in modern times.

Such morphological similarities give a clue that the newly-found fossils are early members of Roridulaceae. As Schmidt said, carnivorous plants had been discovered in many plant families today and each had its their own approach to catching prey.

As this specific trap is quite unique to the plant in South Africa, this lineage was previously considered to be of Gondwanan origin, most of which usually live in the southern hemisphere. But now it seems that the newly-found fossils could widen the distribution of roridulid plants as well.

Journal reference: Sadowski, Eva-Maria, et al. “Carnivorous leaves from Baltic amber.”Proceedings of the National Academy of Sciences 112.1 (2015): 190-195.