Safely rooted, most plants' nutritional requirements are amply supplied by their local environment. But where the pickings are poor and nitrogen is scarce, some species have opted for an unorthodox dietary alternative. They've become carnivorous, developing specialised appendages to trap and digest unsuspecting victims. How one group of carnivorous plant - pitcher plants -detain their victims intrigues Elena and Stanislav Gorb in Stuttgart, Germany(p. 2953).

Focusing on Nepenthes ventrata's pitcher, they investigated the surface properties of the plant's digestive gland tissue. Testing the tissue's surface properties on insects equipped with claws or adhesive pads, the Gorbs'team found that insects with specialised attachment pads could cling easily to the pitcher's rough digestive surface, while insects with claws alone probably couldn't get a grip unless they dug into the pitcher's walls. And the plant's digestive juices didn't seem to affect the ability of flies to get a grip,although bugs found the surface slippery when coated in the plant's secretions.

The team suspects that `the glandular surface is probably not responsible for prey capture and retention', and the insect's fate is most likely sealed by the pitcher's upper waxy surface and lid.

Gorb, E., Kastner, V., Peressadko, A., Arzt, E., Gaume, L.,Rowe, N. and Gorb, S. (
). Structure and properties of the glandular surface in the digestive zone of the pitcher in the carnivorous plant Nepenthes ventrata and its role in insect trapping and retention.
J. Exp. Biol.