Thus he rails in speeches against the menace of a "sixth extinction," one unlike the prior five extinction spasms, the last of which came 66 million years ago. Those were brought about by natural phenomena. When it occurs, the sixth mass extinction of living organisms will be brought about by people, by a mushrooming population that has doubled in 40 years, to 6 billion, and by human carelessness and commerce. In the 21st century, which Raven would like to see called "the age of biology," he says we must learn to "master the diversity of living organisms and use the properties of those organisms as a kind of palette to build sustainability."

Instead of cultivating one garden, he looks to everyone's. He protects, collects, lobbies, studies, preserves and expands his territory. He networks like a press agent but believes it is up to individuals to keep what's living living. "When it ends up," he tells me, "the world is not going to be one homogenized place. It's going to have bright spots, richer places and more beautiful places. And the reason that will happen is that individuals took responsibility and did something." As it was in the beginning, the world is a garden.

So Raven looks to the wide world to build other countries' capacities for sustainable development. Two areas that he regards as especially critical are Madagascar and the northern Andes. Madagascar has half as many plants as all tropical Africa (about 11,000), and the great majority are found nowhere else. The Missouri Garden has been active there since the early 1970s, helping train and support the country in evaluating and protecting threatened areas. In the northern Andes, Colombia, Ecuador and Peru are home to at least one-fifth of the world's biodiversity, including perhaps 60,000 species of plants, endangered by development and poorly studied. The garden has been cooperating with these nations to help them work out their own plans for the wise use of resources. Raven is volubly opposed to anything that smacks of American big-footedness in these endeavors.

His is one of those special minds that succeed with both the particular and the general, with individual and collaborative pursuits. His boyhood in San Francisco was spent roving vacant lots, searching for specimens. An only child, he began growing caterpillars into butterflies at the age of six. At eight he became a student member of the California Academy of Sciences. At 12 he joined the Sierra Club. At 15 he discovered a member of the heather family, a Presidio manzanita, which had not been seen for 50 years. This subspecies, Ravenii, was later named for him. He did his undergraduate work at Berkeley, got his Ph.D. at UCLA and entered teaching, but not a cloister; he also developed a gift for bringing people together for worthwhile projects.