Plants in peril.

At least one in eight of the world's known vascular plant species is under threat of extinction, according to the World Conservation Union's new 7-pound, 800-page 1997 IUCN Red List of Threatened Plants.

The report, released on April 8, 1998, is the first-ever global assessment of vascular plants, which include ferns, conifers, and flowering plants (but exclude mosses, lichens, algae, or fungi). Of the species assessed, nearly 34,000 - 12.5 percent of the 270,000 known vascular plant species in the world - are under threat of extinction. The report is based on two decades of research and collaboration among scientists, conservation organizations, botanical gardens, and museums around the world.

While the reasons behind the decline of plant species can be complex and varied, loss of habitat and the introduction of non-native species are the primary threats. For example, heavy logging of forests in central Chile has reduced the distribution of the coral plant (Berberidopsis corallina) to just a few small groves in the forest. And on the island of Mauritius the introduction of both the strawberry guava plant and monkeys has brought the small tree Elaeocarpus bojeri (a species so rare that it has not been given a common name) quite literally to the brink of extinction as the few specimens that remain cling to the side of a hillside.

Due to insufficient data from some regions, the estimated number of threatened plant species is highly conservative and may well represent "just the tip of the iceberg," the report notes. Countries such as Australia, South Africa, and the United States, for example, have comprehensive assessments of the conservation status of their plant species. However, in most of Africa, Asia, the Caribbean and South America, the data are "more fragmentary and often very incomplete." When these regions are more fully studied, the report states, they "will undoubtedly be found to harbor many more threatened plants than are documented in this edition of the Red List."

Even if incomplete, however, a list this large constitutes an alarming picture. Together with the IUCN's earlier assessments of animal species, which found that 11 percent of the world's bird species and 25 percent of its mammals are threatened, it is starkly clear that the global loss of biodiversity is one of the most significant issues of our time. The world is now losing an unprecedented number of species, and losing them at a much faster rate than they are being replaced. Species that evolved over thousands of centuries are now being lost virtually hour by hour.

The good news, says Bruce Stein, a botanist with The Nature Conservancy, is that because plants are less mobile and may not have the same space requirements as birds or mammals, they are in some ways easier to protect than other organisms. "It is just a matter of getting the commitment and resources to protect them," says Stein.