An Introduction to Carnivorous Plants
All plants need nutrients and most get theirs from the soil, but in some habitats such as bogs they do not get the chance to absorb it in the normal way. So many plants have evolved strategies to cope and this includes plants which get their nutrients from animals. There are many different types of these carnivorous plants which can be found throughout the world.
Pitcher Plants have evolved independently several times. The traps are usually leaves which have been modified in some way to produce a jug shaped trap with water at the bottom. Insects are attracted to the plant by drugged nectar that sends it into a stupor. It then falls into the water at the bottom.
The simplest of these traps are the Heliamphora or Marsh Pitchers of the Tepuis Mountains of South America. These plants have a basic trap consists of leaves which have been modified and fussed together to create the pitcher. They attract their prey with a simple spoon shaped projection. It is thought that bacteria are needed to digest their prey.
More complex are Sarracenia or Trumpet Pitchers of the USA. These are distantly related to Heliamphora but have evolved very elaborate traps. They are often very colourful and the traps grow directly from their tuber. These traps have evolved to attract insects with nectar which is drugged so when their prey tries it they are disorientated. The insect then falls into the pitcher and finds itself unable to get out due to downward pointing hairs. Darlingtonia works in a similar way just enticing the insects with bright lights
Nepenthes are the most famous group of pitcher plants. These vines are found in South Asia and Indonesia. This time the Pitcher forms from a swollen leaf tip which open to reveal a deadly pond of enzymes. These traps also produce nectar, but when the insects fall inside it reaches a waxy band where they slide into the pool at the bottom.
Butterworts (Pingunicula) are the simplest of the passive traps and the insects just stick to their leaves
Sundews (Drosera) take the stickiness to another level. Their leaves are covered in sticky “Dew” tentacles. Even if the insect is trapped by one more tenticles more towards it and is enveloped.
Venus flytraps are related to sundews and take movement to another level. They snap shut when an insect lands on them.
Other plants with similar sticky traps to sundews include the lesser known Byblis, the semi-carnivorous Roridula and The Dewy Pine (Drosophyllum lusitanicum).
Bladderworts (Utricularia) have active traps which are found in the soil or water. They trap their prey as it moves pass sucking them in.
Corkscrew plants (Genlisea) have traps which are formed from the roots which as their name suggests resembles a corkscrew. The prey enters the traps from a slit at the side of a corkscrew shaped tube. The gap is lined with with bristles which prevent the prey from leaving and they are forced to swim up into a chamber where they are digested.