Flowering plants and fungi

The first land plants appeared at least 400 million years ago. They had forked stems but no proper leaves. flowers or seeds. A few closely similar plants still exist: the whisk ferns. which are native to tropical and subtropical regions; and the Tmesipleris group of ferns in New Zealand. Australia and Polynesia.

The oldest known living seed came from a North American arctic lupin. It was found in 1954 buried in frozen silt near Miller Creek in central Yukon. Canada. by a mining engineer named Schmidt. It had been there for 10.000 years. Yet. when scientists planted it. a plant grew which was identical to the modern plant. Modern seed banks keep stocks of seeds in similarly cold. dry conditions so that rare plants are assured of a future.

The window plant. Fenestraria. makes a private greenhouse to protect itself from the harsh sun of the deserts of southern Africa. Most of the plant grows underground. and only a small transparent window is exposed above the surface. The window. which is composed of translucent cells. has two layers. An outer layer blocks the most damaging ultraviolet rays ofthe sun. and an inner layer cuts down and diffuses the light to a safe level for the green photosynthetic tissue deep within the plant body.

The Crystal Palace-a vast structure of glass and iron. built in Hyde Park. London. to house the Great Exhi- bition of 1851 - was inspired by the pattern of a water lily. The designer. Sir Joseph Paxton. had been head gardener to the Duke of Devonshire at ehatsworth. and had successfully grown - for the first time in Europe-the giant South American water lily. Victoria amazonica.

The plant's leaves are up to 2m (7ft) across. and the arrangement of the ribs gives them such strength that they can support a child. Paxton studied the pattern of the ribs and. years later. used a closely similar pattern of ribs and struts to support the roof of his iron and glass palace. The building. which was moved to south London after the exhibition. was destroyed by a fire in 1936.

Two Australian species of orchid spend their entire lives buried in the earth. The only part which ever emerges is a cluster of capsules which are pushed above the surface to disperse the dust-like seeds. Both species feed on decaying plant material in the soil, breaking it down with the aid of fungi.

The first of the two orchids. Rhizanthella gardneri. was discovered in 1928 by a Mr J. Trott. who ploughed it up by accident on a farm in Corrigin. Western Australia. The second. Cryptanthemis slateri. was discovered by a Mr E. Slater in 1931 at Alum Mountain in New South Wales. Very little is known about either species because very few specimens have ever been found.

The largest seeds in the plant kingdom are also the most mysterious. The seeds - which belong to the double coconut or coco de mer. Lodoicea maldivica - take up to ten years to develop. before they are ready to grow into a new palm tree. They look like two coconuts joined together, and can weigh up to 20kg (44Ib) each. In the wild they grow almost invariably on hilltops on remote islands in the Seychelles.

What baffles scientists is how the seeds got there. Since the seeds are so heavy, the trees might be expected to spread downhill as each generation of seeds falls from its parents. But how could the seeds travel uphill to colonise a new peak? No native animal or bird would be capable of carrying them, and since they sink in water, they cannot have been carried up by the sea.

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