From salad to steak, everything we eat comes from plants. We build with wood, and plants supply the oils, fibers, chemicals and gums we use to create a wealth of industrial products. Three-quarters of the people on Earth rely directly on plants for medicines - in industrialized nations, a large percentage of prescription drugs are based on chemical compounds derived from plants.

And we are just one species in millions. Plants provide habitat for animals, protect watersheds and topsoil, convert greenhouse gases to oxygen, and regulate local climates, forming the foundation of the elegant, interdependent web of life.

Yet the potential has barely been tapped. Fewer than one-eighth of Earth's plants have ever been evaluated for human use, and just 103 species supply over 90 percent of all foods on the market today. Screening for anti-cancer and anti-HIV compounds in plants has just begun - we have merely scratched the surface.

Despite our dependence on plants, today we are heedlessly destroying species at a headlong pace in every country around the world. Most losses will occur in the tropics, where biological diversity is richest.