Dried, sorted and stored at minus 4 degrees Fahrenheit they sit in glass jars in vaults, awaiting the day the scientists hope will never come -- when the species no longer exists in the wild.

"Environmentalists talk doom and gloom. This is our way of doing something about it. It may not be a lot, but at least we are doing something," project head Roger Smith told Reuters.

"This project is as much about people as about plants. This is the start of something, not the end. What we have here will be a vital resource for the world."

The goal of the $127.3 million project is to collect 10 percent -- or 24,000 species -- of the world's seed-bearing plants by 2010.

Half of the seeds of each species will be stored in the Millennium Seed Bank's vaults, with the other half remaining with the responsible institution in the country of origin.

The seed bank, which makes its facilities available to scientists from the co-operating partner countries, carries out extensive testing to determine the optimum conditions for planting and germination.

This data is shared freely with the partner country -- of which there are currently 16 -- to help it set up re-establishment programs in places where the plants have been over-exploited for food, fuel or medicines.

"We are growing the seed collection and growing the information collection. We are deepening the knowledge about each species," said Michael Way, co-ordinator for the Americas. "We are building information bridges."

But while countries as diverse as Saudi Arabia and Canada have willingly signed up, others such as India and Brazil have either been reluctant or refused point blank.

"Brazil won't have anything to do with us. They have refused to let us have any seed," Smith said. "They have a thing about not letting and seeds out of their hands.

FEAR OF BIO-PIRACY

"India has also been difficult. They have black pepper. It is a very important crop to them and they are scared of losing it. But we are not talking about black pepper. We are talking about bio-diversity."

There is also a certain amount of historical baggage to be shed on route. Britain has a colonial legacy to confront and Kew Gardens -- under whose name the Millennium Seed Bank runs -- was no stranger to Victorian era bio-plundering.

"You have to confront it. You need infinite patience. Sometimes in meetings I have to try to prove I am not a bio-pirate," Smith said.

The team, which started with just 14 people at Kew's seed conservation department and has now grown to more than 40, sends out teams to partner countries to train people in the delicate art of seed collecting -- some are tiny, others well protected.

It also acts as a catalyst, bringing together scientists from the different countries and even institutions within the same country, many of whom have never communicated with each other.

"We are capacity building. We are acting before it is too late. This is not a big thing, but we have to start somewhere," said Moctar Sacande from Burkina Faso, and head of the Seed Bank's sub-Saharan tree seed collecting Darwin Project.

And time is running out.

Scientists estimate that within half a century a combination of climate change and environmental pressure will put quarter of the world's plant species on the condemned list.

The consequent loss of animal life and to humans is incalculable but certainly catastrophic.

But already the Millennium Seed Bank is running out of money and will have to hit the fund raising trail next year.