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Carnivorous plants

About a thousand different plant species are now known to be "carnivorous". Their prey can range from microscopic unicellular animal organisms to insects and small vertebrates to small birds and even rats.

Diversity

Carnivory independently developed several times in the plant kingdom. Carnivorous plants are widespread all over the world.

In Germany there are 15 carnivorous species from four genera: Sundew (Drosera), Bladderwort (Utricularia), Butterwort (Pinguicula) and the endangered Waterwheel Plant (Aldrovanda vesiculosa). All native species are strictly protected in our country.

The Bonn Botanic Gardens have one of the most extensive carnivore collections in the world. About 300 different species are cultivated here. There are extensive research projects on these species at the Nees Institute.

Aldrovanda_vesiculosa_W.Barthlott_Lotus-Salvinia.de.jpg
Waterwheel plant (Aldrovanda vesiculosa) © W. Barthlott, Lotus-Salvinia.de
Drosera_binata_var_dichotoma_1833_W.Lobin.jpg
Carnivorous plant (Drosera binata var. dichotoma) © W. Lobin / Universität Bonn

Traps and species

Plants evolved different and very sophisticated techniques and trap types to capture their preys.

  • Pitfall traps: pitcher plants (Nepenthaceae).
  • Flypaper traps: sundews (Drosera) and butterworts (Pinguicula).
  • Snap traps: Venus flytraps (Dionaea) and waterwheel plants (Aldrovanda).
  • Bladder traps: bladderworts (Utricularia)
  • Lobster-pot traps: corkscrew plants (Genlisea)

All traps are modifications of leaves or parts of leaves.

Various carnivores can be seen outdoors behind the Victoria House. They display different trap mechanisms: pitfall, flypaper and snap traps.

Eine Wissenschaftlerin und ein Wissenschaftler arbeiten hinter einer Glasfassade und mischen Chemikalien mit Großgeräten.
Pitcher plant (Nepenthes rajah) © W. Lobin / Universität Bonn

Pitfall Traps

In this relatively simple trapping mechanism, the prey slides into a "digestive pool" filled with digestive fluid.

Cistern traps (Brocchinia, Catopsis)
Pitcher traps (Cephalotus, Nepenthes)
Tube or tubular traps (Sarracenia, Darlingtonia and Heliamphora)
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Dove leaf (Drosophyllum lusitanicum) © C. Löhne / Universität Bonn

Flypaper traps

The attracted preys are held by a viscous secretion and suffocated. Some species can even actively move their catching apparatus.

Sundews (Drosera)
Butterworts (Pinguicula, Drosophyllum lusitanicum)
Rainbow plants (Byblis)
Dewsticks (Roridula, Triphyophyllum peltatum)
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Venus Fly Trap (Dionaea muscipula) © W. Barthlott, Lotus-Salvinia.de

Snap traps

The trap snaps only if the prey lands on the movable leaf blade and comes into contact with special trigger hairs several times at short intervals. In this case, the trap snaps shut within seconds.

Venus flytrap (Dionaea muscipula)
Waterwheel plant (Aldrovanda vesiculosa)
Eine Wissenschaftlerin und ein Wissenschaftler arbeiten hinter einer Glasfassade und mischen Chemikalien mit Großgeräten.
Utricularia reniformis x nelumbifolia © W. Lobin / Universität Bonn

Bladder traps

In terms of complexity and speed the suction trap of the bladderworts (Utricularia) is superior to all other carnivorous plants. The trapping movement takes about 1/500 seconds, and it is one of the fastest movements in the whole plant kingdom. The prey is sucked by water suction into a bubble-like trap, where low pressure prevails.

Eine Wissenschaftlerin und ein Wissenschaftler arbeiten hinter einer Glasfassade und mischen Chemikalien mit Großgeräten.
Leaf rosette and cage leaves of Genlisea margaretae © W. Barthlott / Universität Bonn

Lobster-pot traps

A particularly sophisticated type of trap, a fish trap, is found in the genus Genlisea. In addition to the normal above-ground leaves, the corkscrew plant forms underground cage leaves. Tiny unicellular organisms - protozoa - are lured inside this cage system. Specialized cage hairs prevent the prey from escaping.