h minimum water has been accommodated to, but heavy daily drenchings can just as equally cause problems. In South America, where Venezuela, Guyana and Brazil all meet, stands a group of massive rectangular, plateaux. Their flat tops rise above the clouds and their vertical rock walls are cascading with surging waterfalls. The biggest of these is Roraima, nine thousand feet tall and ten miles long, it is sometimes called, the Lost World. It arouses images of a prehistoric place and indeed the mountain contains species that can be found nowhere else on earth, but the Roraima does not house survivors from a past age but unique species, isolated on its summit that have evolved extraordinary abilities to enable them to exist in an environment with the worlds heaviest rainfall.For simple plants like algae, Roraima provides an excellent habitat but for more complex ones, life on the water-drenched rocks proves more difficult. The sodden earth supplies very little in the way of nutrients, so the plants must find other ways of finding food. Bladderworts flourish here, they are water plants that are found in wetlands all over the world and they are so expert in trapping animals that they do not grow roots at all. Their traps, little translucent capsules are able to absorb water and as they do they create a partial vacuum inside. The entrance is lined with sensitive bristles and if a small water creature touches one of these it acts as a lever, collapsing the entrance of the capsule. In then rushes the water bringing with it the creature and imprisoning it within a fraction of a second. The bladderwort then releases a digestive acid and within two hours it will have dissolved and consumed its victim and set its trap again.Another plant that prospers below the surface is water celery, they absorb all the oxygen and carbon dioxide they need from the water around them and it also utilises the water to pollinate. The female flower opens its...
