The kurinji blooms just once every 12 years. But are its days numbered?

Far up in the Nilgiri hills, a vast expanse of grassland at the southern edge of India's Western Ghat mountain range, the verdant landscape is usually only interrupted by a flash of colour from tea plantation workers and their brilliant saris.

But once a decade the hills above the tea fields erupt in an explosion of blue and purple, thanks to the kurinji plant, a tiny flower that blossoms just once every 12 years and is found solely in the southern Western Ghats.

This year the kurinji is flowering across the Nilgiri hills in the states of Kerala and Tamil Nadu, but its numbers are much reduced. Over-development in the region and the introduction of non-indigenous plant species have destroyed much of the kurinji's habitat - and environmental campaigners are concerned it may soon disappear altogether. In Kerala there are now just 14 square kilometres of suitable grassland left on which kurinji can grow.

"When we first started work in 1982 you could see the kurinji all over the Nilgiris as it blossomed," said G Rajkumar, a bank employee from Thiruvananthapuram who now leads a campaign to help protect the flower. "Now those areas have been massively reduced. Even though it only grows above 5,000ft, it is ultimately people that are responsible for its demise."

The fragile ecosystem of the Nilgiri hills has found itself under pressure as tourism booms and commercial plantations seek to cash in on India's burgeoning economy by planting numerous species of non-indigenous trees, especially acacia, pine and eucalyptus trees. As demand for cash crops grow, so do the plantations.

During the summer, hordes of local and foreign tourists journey up the mountain passes to the cool hill stations that dot the Western Ghats, escaping the oppressive heat in the plains below and sampling the only tea grown in south India. The result is a major water shortage which, environmentalists warn, threatens to damage the kurinji's natural habitat.

As the flowers blossom this summer, the worst fears of environmentalists appear to have come true.

The loss of the kurinji would not only be a huge blow to science but also to south India's long cultural heritage, which lends the plant near mythical status.

"It's impossible to digest that fact and accept it," John Britto, a local botanist and a Jesuit priest, told the Los Angeles Times this week. "As a person of this land, a culture, it would be a terrible loss. We are wedded to the soil, the land, to the plants, and that link between man and nature is getting lost. That's irreparable."

Although Western botanists first recorded the flower blossoming in 1858, the indigenous hill tribes of the Nilgiri have long venerated the little blue flower in their local customs and folklore. One tribe, the Muduvar, use the kurinji's blossoming to help calculate their age.

Tamil poems dating back more than 2,000 years praise the karungal kurinji (literally "black-stemmed flower") and the honey made from bees that feed on its nectar. Hindu mythology records the god Murugan wearing a garland of the flowers at his wedding to a local girl.