Gorse putting on a great display of golden blooms

Jim Hurley - Nature Trail

Published 21/04/2015 | 00:00

Gorse is a member of the large pea or legume family.
Gorse is a member of the large pea or legume family.

Gorse is putting on a magnificent display of flowers this spring with many islands of wayside hedgerows aglow with its golden blooms.

Gorse is a member of the large pea or legume family. All members of that large family share a common and diagnostic flower structure as shown in the image above. Another diagnostic feature of most legumes is symbiosis.

Symbiosis literally means 'living together'. It is a close and often long-term relationship between two or more different species. The different species live together for their mutual benefit.

Symbiosis is no stranger to ourselves. We support a large community of bacteria in our intestines. We provide the bacteria with a warm, safe home, free board and lodgings and in return they break down otherwise indigestible carbohydrates for us as well as providing other services.

The relationship is mutually beneficial to ourselves and the many bacteria that comprise our gut flora.

Gorse and other legumes also support symbiotic bacteria. Many legumes provide a home for bacteria that belong to the group called Rhizobium and feed them. In return the bacteria take nitrogen gas from the air and supply it to the legume in the form of ammonia that the plant can use to help it grow.

Nitrogen is a very common gas in the air but legumes are unable to extract it from the atmosphere themselves. Rhizobium provides that service and in return the legumes provide homes and food for the bacteria in special swellings on their roots called nodules.

Nodules were noted many centuries ago but nobody knew why legumes had them. The early scientific explanation was that the bump-like lumps were insect galls.

Clover is a legume and it is noticeable on lawns that the grass is usually greener around a patch of clover due to the greater presence of nitrogen compounds in the soil due to the activities of Rhizobium.

Scientists are researching exactly how Rhizobium fixes nitrogen and what genes are involved in the process. The results could have profound impacts in agricultural output by increasing plants' productivity without using artificial fertilisers.

Artificial fertilisers rich in nitrates get leached from farmland by rain and find their way into groundwater and water courses when they become a significant contributor to problems associated with high nitrate levels in drinking water.

Excess nitrates in rivers and lakes also disrupts the natural balance in the vegetation resulting in algal blooms and pollution.

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