Mould can taste - and do good too

You have probably seen a piece of very stale bread covered with small fluffy, bluish growths.

But eating a small amount with your bread would not actually harm you. These growths are mould, which belong to the large group of simple plants called fungi.

There are nearly 100,000 different kinds of fungi.

Some are very beneficial. Certain moulds are used as flavourings in blue-veined cheeses, and the mould Penicillum notatum is processed to make the antibiotic wonder-drug penicillin.

Some fungi take their food from the tissues of living plants and animals, while others feed on dead and decaying plants and animals. This helps break down dead bodies, leaves, old wood and waste matter into simpler chemicals that can be re-used by plants.

But moulds can also be harmful and destructive. Several species grow on cotton, glass, paints and leather. Others attack wood and can be a real nuisance in old buildings.