Madagascar pitcher plant (Nepenthes madagascariensis) in the Berenty Reserve, Madagascar. Pitcher plants are carnivorous and use scent, nectar and colour to attract insects. The interior of the 'vase' or 'trumpet' is slippery and contains downward-pointing spikes so that once an insect has entered it will be unable to leave, slipping to the bottom. Liquid at the base contains digestive enzymes which digest the insects and provide phosphorus and nitrogen for the plants. These plants are classed as an endangered species.