One of the world’s rarest plants, the Lundy cabbage, has been brought back from the point of extinction.

The cabbage, which, despite its beautiful yellow flowers, tastes disgusting, is found only in a couple of hundred square yards on Lundy Island, a few miles off the North Devon coast.

It is enjoying its most successful year in decades, thanks to conservationists’ attempts to stop an invasion of rhododendrons on the island.

The Lundy cabbage (Coincya wrightii) is one of the few plants endemic to Britain but was being driven out of its cliff-face home by the tougher rhododendrons.

Attempts to stop the rhododendrons began in the 1940s, when volunteers were called in to cut them down. But the plants came back stronger every time, so in 2002, conservationists began a full-scale extermination programme.

Stephen Crompton, of the University of Leeds, one of the scientists working to save the Lundy cabbage, said: “It’s looking very good at the moment. The cabbage is really taking advantage of the areas cleared. In some places the cabbages are right up to the cut line.

“It’s been a total turnaround really. If and when the rhododendron is cleared, it will be the first eradication of an alien plant on this scale in Europe.”

The cabbage’s fortunes fluctuate on open areas of the island because of the rabbit population, but it had been safe on the cliffs until the arrival of rhododendrons. “The problem has been that wherever the cabbage can grow, the rhododendron can grow. If left unchecked there would eventually be no cabbage left,” Dr Crompton said. “But we’ve had no rhododendrons flowering on the cliffs this year — that’s the first time that we know of.”

A target of 2012 has been set for the eradication of the rhododendrons on the island. The cabbage evolved from another species of wild cabbage living on sand dunes and which colonised the Bristol Channel area at the end of the last Ice Age. As the ice melted, sea levels rose and Lundy, until then a promontory, became an island, where, without any dunes, the cabbage evolved to live on cliffs.

Roger Key, of Natural England, said of the cabbage: “It’s something that is absolutely unique to the United Kingdom and there are remarkably few things that are. What’s more, it’s related to commercial crops. It’s a potential genotype source that may one day be vital to developing new varieties to feed the world.”

Specific genes from the cabbages could be used to help to create new varieties, he said, but he doubted that the whole plant would be cultivated as a food crop.

Dr Key is one of the few people to have tasted the plant, having been granted a licence to pick one for research.

“We got a knob of butter and sweated it. It took about three days to get rid of the concentrated smell of brussels sprouts,” he said. “It was unbelievably disgusting. It’s everything that any seven-year-old hates about cabbage multiplied fiftyfold. Technically it’s edible but you wouldn’t have a second bite.”

The recovery coincides with the discovery that a weevil living on the cabbage is a separate species. Entymologists had known of the weevil’s existence, but thought that it was the same as a pest species on the mainland.

A search around Europe and North Africa revealed that the insect, now called the Lundy cabbage weevil

(Ceutorhynchus contractus var. pallipes), is found only on the island and in part of northwest Spain.

It lives alongside and competes for space on the cabbage with the Lundy cabbage flea beetle, a species that is found only on the island and that has also been given a more secure future by the rhododendron clearance.

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