Thursday, October 30, 2008

Insect eating plants

Although green plants are self-supporting as far as their food requirements go, some plants do rely to a certain extent on other living creatures. One group of these, known as insectivorous plants (plants which live on insects), gain part of their nourishment by trapping insects in various ways. The plants digest the insect's bodies and take the dissolved proteins into their systems. Several of these interesting plants occur in Europe, and there are many others in tropical countries, often large and with weird methods of trapping insects. Insectivores are usually plants of marshes and bogs where the soil is poor in the nitrogen compounds so necessary for their continued healthy existence. Although they are mostly green plants, producing some of their own food, they do need the proteins of the insects to make up the lack of nitrogenous food.

Some plants produce hollow leaves containing liquid in which the insects drown, the Sarracenia being an example of this. The leaves are rather funnel-like with a lid to the opening at the top. The rim of the funnel has nectar to attract insects, and the whole plant is often brightly colored. Inside the funnel is a slippery area, and downward pointing hairs, which prevent any insects crawling out again. Nepenthes, the pitcher plant, produces curious pitcher-shaped extensions to the leaves which act in the same way as Sarracenia. They are usually climbing plants rather than bog plants, and are widely grown in greenhouses in hanging baskets. In both of these plants, the insects bodies are decomposed in the watery fluid at the base of the pitcher, which contains many bacteria, the plant then using the dissolved substances.

No comments: