The lifelong obsession with moss paid off for the National University of Singapore (NUS) don earlier this month, when he was awarded one of the most prestigious awards given out in the field, the Richard Spruce Award.

The award was given in recognition of his important contributions to bryology - the study of mosses, liverworts, and hornworts - while he was in Venezuela attending a meeting of botanists.

It came as a total surprise to him.

Said Associate Professor Tan: 'I was overwhelmed when I heard my name being called because this means international recognition of my research contributions in bryology.'

Along with a plaque, the award - given by the International Association of Bryologists, which has about 600 members worldwide - included an invitation to give a special lecture at the next bryological world congress in Vienna next year.

Prof Tan, who is from NUS' department of biological sciences, is the fourth recipient of the award in 10 years, but the first from Asia.

During the award presentation on Jan 15, the association's president, Dr Robert Gradstein, who is from Germany, said that Prof Tan was recognised for the 25 years he has spent documenting the diversity of Asian mosses.

He also praised him for identifying 'hot spots' in the region where mosses proliferate, and for his efforts in campaigning for the protection of such areas.

Although he has been called crazy because of his passion for mosses, Prof Tan, who has three species of mosses and liverworts in the region named after him, says that his interest is not purely academic.

Such plants, he says, contain special compounds that can be found nowhere else.

And although these have not been well studied, they could one day be made into drugs to treat diseases.

German scientists, for example, have found that some moss extracts can kill fungi more effectively than commercial fungicides.

Other studies found that peat moss apparently stimulates pigs to feed and grow.

Prof Tan has also compiled online databases on regional moss species and endangered species elsewhere.

Just this month, he and two of his students discovered two new moss species here.

One of only a handful of such experts in South-east Asia, he has braved everything from tribal wars and broken bones to close encounters with snakes and other dangerous forest creatures during his travels to some of the most remote spots in Asia.

His unceasing hunt for new species has taken him to places such as Eastern Siberia, Vietnam, China and Papua New Guinea.

'Rather than just following trends of what's 'hot' in the research world, it pays for a scientist to be committed to one field of study, although it may not seem glamorous at the time,' said Prof Tan.

'In the end, bits of information accumulated over the years will build up a big picture that has important implications.'

There are about 18,000 species of bryophytes, which reproduce using spores rather than seeds, worldwide.

About 2,000 of them can be found in the region.

Mosses play a major role in the forest ecosystem, as many animals and insects rely on them for food.