Scientists have announced plans for a global plant rescue scheme.

It is the brainchild of a team of plant experts working with the International Union for the Conservation of Nature (IUCN), a Swiss-based scientific body known also as the World Conservation Union.

They are "poised to launch an international program to conserve the species that form the cornerstone of human existence - the world's plants and trees".

The scientist who chairs IUCN's Species Survival Commission (SSC), David Brackett, said: "We live in one of the most expensive decades of the most expensive century in history, when measured in terms of the loss of the unique diversity of life on this planet".

Details of the scheme were announced at the 1999 International Botanical Congress. The meeting, held once every six years, is currently taking place in St Louis, Missouri, and is being hosted by the Missouri Botanical Garden.

Major threat

The SSC includes about 7,000 volunteer scientists and conservation professionals. Last year, it said more than 34,000 plant species - about 12.5% of the world's flora - faced extinction.

Extinction rates now rival the five great waves of the distant past

The IUCN's plants officer, Dr Wendy Strahm, said biodiversity loss was "one of the greatest threats to our future".

"The situation is dire. We must mobilise botanists as well as decision-makers to ensure that the massive loss of species and variation that we are losing today is stopped."

The scientists planning the emergency rescue plan say the issues involved in plant conservation are complex. They include protecting "hot spots" with high concentrations of species, the sustainable use of medicinal plants or others important for human purposes, and the effects of invading species.

They have drawn up a list of the conditions to be met to ensure the survival of threatened and important plants, including:

• sound scientific information on which to base decisions and policies;
• an immediate focus on hot spots, especially those under pressure from human influences;
• rigorous criteria to identify sites of high plant diversity;
• reducing the effects of invasive plants (and other species);
• promoting sustainable use and training programmes for botanists.

Three days ago, the Congress president said humanity's impact on the Earth had increased the rate of species loss to levels comparable with the five mass extinctions of geological history.