Most tropical plants grow in tropical rainforests found around the world, including those in the Amazon River basin, Indonesia and the Congo basin. While scientists know much about the tropical plants growing in these areas, they believe lots of plants still exist that no one has yet documented.
Types of Plants
Tropical plants grow in one of the four layers of the tropical forest. The tallest trees reaching 200 feet or more in height appear on the top, or emergent, layer. The next layer down, the canopy layer, contains trees that grow up to 150 feet tall. Most of the other tropical plants that make up the forest live in the understory. The understory only receives 2 percent to 5 percent of sunlight. Plants growing in the understory sport dark leaves that collect the available sunlight. They rarely grow more than 12 feet tall. The lowest level in the rainforest contains almost no plants since so little sunlight filters through.
Some of the plants in the understory grow huge flowers and fruits low on their trunks to encourage animals to eat and disperse the fruit so they can spread. One plant, the Nepenthes rafflesiana, similar to the Venus flytrap, sports a large 12-inch trap where insects get stuck when they land. Small animals and reptiles who try to nab the insects get caught in the trap, providing a hearty meal for the plant. Other plants, such as orchids and epiphytes, use nutrients and moisture from the air to grow, with some of them never touching the ground during their lifetime.
Besides providing food and habitat for the tropical forest's wildlife, some plants, such as the liana, help the animals move through the forest's canopy. Woody, vine-like plants, lianas form thick, ropy vines that latch onto other plants for support to grow toward the canopy where more sunlight exists. The thick, long ropes help wildlife such as sloths, lemurs and spider monkeys to move through the forest. Thanks to lianas, some of these animals never even touch the forest floor.
More than 2,000 tropical plants identified by scientists contain anti-cancer properties, yet less than 1 percent of the plants have been analyzed to see if they, too, contain medicinal value. More than 25 percent of the ingredients used in cancer-fighting drugs come from tropical plants.
More than 25,000 types of orchids grow in the rainforest with the Cooktown orchid and the moth orchid, among others, listed on the endangered species list. Illegal collecting of the plants and deforestation through logging often contributes to the growing list of endangered orchids. Another tropical plant, the rafflesia, remains on the endangered list because it requires specific host plants on which to feed. The host plants only grow in a particular area of the tropical rainforest, giving the rafflesia very few opportunities to spread.