Do all plants use photosynthesis?

Not all plants use photosynthesis to create the proteins of their food supply. Instead, they live off other plants and animals, working in the darkness. Some can even be killed by too much exposure to light. Such plants are the bacteria and the fungí. They are nature's rubbish disposal operatives.

A study of bacteria and fungí may one day lead us to solve the two great mysteries of how life began in the sea and how plants first invaded the land. Some species of bacteria are able to build up protoplasm, the living matter of a cell, from carbon dioxide and chemical salts by a process called chemosynthesis. This is similar to photosynthesis, but takes place in the absence of light. Such bacteria may be not unlike the primitive forms of life first produced on earth.

Fungi, on the other hand, in their structure and behaviour resemble seaweeds and may be a development from the first plants to climb ashore and adapt themselves to life on the land. The question of which carne first, the photosynthesising green plants or the seaweed-like fungí that learned to live off them, remains unanswered.