Cultivating trouble
Only 39 percent of the nearly 10,000 North American plant species threatened with extinction are being maintained in collections, according to the first comprehensive listing of the threatened plant species in Canada, Mexico, and the United States. The North American Collections Assessment (NACA) — conducted collaboratively by Harvard’s Arnold Arboretum, Botanic Gardens Conservation International U.S., and the U.S. Botanic Garden — found that only 3,681 of North America’s 9,494 most threatened plant species are maintained in 230 collections across the continent. Although the protection of natural habitats remains the highest priority, maintaining rare species in seed banks or living collections — such as those in public gardens and conservation organizations — provides an insurance policy against future loss. Such collections have also been valuable in restoring natural populations. “Until this point, nobody knew which rare North American plants were safeguarded in collections,” said Michael Dosmann, curator of living collections at the Arnold Arboretum...