Carnivorous Plants - A Natural History
Created | Updated Feb 26, 2007
Carnivorous Plants are plants that instead of just getting nutrients they need from the soil feed of animal food. They live mainly on insects but some live on rats, and frogs.
There are many different families of carnivorous plant found all over the world.
Trap Types.
Many carnivorous plants use similar methods to trap prey (An example of parallel evolution) So it is best to introduce them by looking at how they trap their preyThere are 4 main different types of trap with many different subtypes
Pitcher trap:
The pitfall or pitcher trap is usually a leaf that has fussed together to produce a tube with water as the bottom of it. The insects are attracted to the plant by a nectar like substance that sends the animal into a stupor. The insect then falls down into a slippery part of the trap and into the water below where digestive enzymes get to work on the insect's body
The simplest example of this type is Heliamphora: The Marsh Pitcher of the tepuis Mountains. This family have a very simple ground growing trap which is just a leaf fussed together to make a trap that fills with water, they also have a simple spoon to attract insects and bacteria digests their prey.
Sarracenia: The trumpet or North American Pitcher plants from the USA are closely related to Heliamphora but this family has very much more elaborate traps, which are usually brightly coloured and also grow on the ground. These traps also have nectar, which attracts the insects and makes them drunk or loss their senses. The insect then falls into the pitcher and finds itself in an area with downward pointing hairs so the insect can only go further into the trap and cannot escape.
Darlintonia: The Cobra Lilly is closely related to Sarracenia and use a similar method but with one difference, they confuse the insects into thinking that there is a way they can through the trap, in fact these are only fake windows and the insects are stunned and fall into the trap
Nepenthes are the most elaborate pitfall traps, these vines grow in south Asia and Borneo. The pitcher is formed from a swollen leaf tip and contain the largest species in N.raja which has been known to catch rats who have been drowned after coming to drink water from the trap. The traps like Sarracenia produce a nectar which attracts insects to the trap but then once they have fallen into the pitcher the insect reaches a waxy area where it cannot keep its foot hold and thus falls straight into the digestive juices below.
Sticky trap:
Sticky traps are simply where the insects are trapped by a sticky substance and there are two different types:
Butterworts (Pinguicula) work by looking perfectly normal so there is no sign the plant is carnivorous - basically it works like fly paper and does not attract the flys - they just wait for any which happen to be about.
Sundews (Drosera) are more complex - they attract the insects by looking like glistening nectar confusing the insects into landing on them - once they have it's a different story because the glistening drops are really drops of glue on the tip of long tenticles which stick to the insects and block their pores. As the insect struggles more of the tenticles move towards them so there is no escape even if they where only caught by one tenticle orginally... Sundews are found in bogs all over the world and include tropical and temperate forms.
Venus fly traps:
The Venus flytrap (Dionaea muscipula)uses a different method: the "snap trap" in which a fly lands on the trap and touches a tiny hair, if the insect touches the hair twice in twenty seconds then the trap snaps shut. Very little about how this happens is known what is known is that the stimulus that triggers the reaction is an electric signal similar to nerves in animals. However even though it is slower than in humans it is very fast.
Bladderworts
Bladderworts (Utricularia) are the underground or water based carnivorous plant - they trap the insects by having a bladder that grows off the main stem of the plant. The bladder has large guide hairs growing out of it; these guide the insects towards the closed mouth of the trap. At the mouth of the trap there are trigger hairs which trigger the trap to be opened then the insect touches them and the insect is sucked inside. This happens because the bladder has a vacuum inside it and is thus concave so when the trap opens water rushes into it. After the insect is caught any water is pumped out again.
Flowering
How do carnivorous plants prevent their pollinators from getting eaten, this is a problem for which many solutions have evolved.
The North American Families
Sarracenia with their tall handsome flowers are usually much taller than the pitchers adding about the same in height again. They are usually pollinated by bees, which enter through petals onto an internal platform they then have to get through the stamen and onto stigma where they are pollinated and only the bees know where the nectar is.Sundews and Venus flytraps
Sundews and Venus flytraps both try and become as tall as possible. They tend to have small flowers and only a few species have larger ones. Many are self-fertile which means that if they are too effective at trapping their prey they can still reproduce
Butterworts and Bladderworts
The reason both butterworts and Bladderworts are in the same section is because they are closely related. In Butterworts the flowers are on a tall stem. In both Butterworts and bladderworts the pollinators tend to be large flying insects possibly bees or moths in many cases
Nepenthes
Nepenthes flowers consists of a large number of tiny flowers on a large spike, they have 4 short tepals from which the male or female parts emerge , they produce nectar to attract pollinators such as beetles and flies, however it is thought that much of the pollen is transferred by windWhere to see them in the wild
Sarracenia can be seen all over the America, however the best place to see them is the Everglades in FloridaDarlingtonia is native to the Rockies
The Venus Flytrap can only be found in Southeastern north Carolina
Sundews can be found in every continent except Antarctica, the tropical species occur mainly in Queensland Australia. 3 temperate species are native to the UK and can be found in Scotland.
Butterworts can also be found in the UK and in the Scottish highlands. The tropical species occur in Mexico
Bladderworts are found all over the world and are also found in the UK
Borneo is by far the best place to see Nepenthes as 32 species of these plants are found there; many are found on Mt Kinabalu including N.Raja. Nepenthes are found all through that area of Islands.
Did You Know?
The name Nepenthes comes from the drug Nepenthe in the Illiad used to alleviate sorrow and grief.
Charles Darwin was the first person to find out that sundews are carnivorous – He was also the first person to write a good about the natural history of carnivorous plants
There are two species of carnivorous bromeliads
BBC LINKS
Carnivorous Plants are even found in the UK - Here is an article from BBC Wildlife on carnivorous plants native to the UK
EXTERNAL LINKS
The Carnivorous Plant Webring is a good place to look for more informationSources
The Savage Garden: Peter D’AmatoPrivate Life of Plants: David Attenbough
