THE DIVERSITY OF LIFE FORMS
The Malaysian rainforest is a complex ecosystem that is made up of mainly tree species. However, within the forest, a variety of other plants flourish, including climbers, epiphytes, herbs, parasites, saprophytes, shrubs and stranglers. In waterlogged areas, specialized habitats occur, such as freshwater and peatswamp forests, mangroves, rivers and lakes, where various types of aquatic plants can be found.
Plants can be classified into two major groups: autotrophic and heterotrophic. Most plants are autotrophic, that is, they possess chlorophyll and are able to perform photosynthesis. Heterotrophic plants, on the other hand, are devoid of chlorophyll and therefore unable to photosynthesize. These include the holoparasites, such as Balanophora and Rafflesia, and the saprophytes, like fungi and a few orchid species.
Herbs are well represented in Malaysia in families of both dicotyledons and monocotyledons. In size, they range from a minute plant of a few centimetres, such as the Corybas orchids, to lofty herbs a few metres tall, like the banana plants. Climbers are weak-stemmed plants whose long, slender and fast-growing shoots require other plants or firm objects for support. Epiphytes are plants that grow on other plants, perching on the branches and other exposed parts of the host in order to obtain adequate sunlight and rainwater. Plants that start life as epiphytes but later send roots down to the ground are called stranglers. On reaching the ground, the roots increase in number and size and eventually encase and strangle the host tree. Many species of figs have adopted this growth habit and are frequently seen in the lowland forests of Malaysia.
Most species of fungi and a few species of vascular plants have evolved into a saprophytic way of life. They do not possess structures that enable them to obtain nutrients directly from the environment, and are entirely dependent on decomposing organic material for their growth and reproduction. Lichens are organisms comprising fungi and blue-green algae in a symbiotic relationship. In Malaysia, they are found in damp habitats at all altitudes, and on rocks, walls of old buildings, tree trunks, branches and leaves.