Rural residents of developing countries depend on plant resources for up to 90 percent of their total material needs. Loss of habitat, pressure from non-native species, and overharvesting have put one out of every eight plant species at risk of extinction, according to the World Conservation Union. Those that we rely upon most heavily are declining too. Some two thirds of all rare and endangered plants in the United States are close relatives of cultivated species. Crop breeders often turn to wild relatives of crops for key traits, like disease resistance, when they cannot find those traits in cultivated varieties.
Many medicinal plants are also in trouble from overharvesting and destruction of habitat.
The bark of the African cherry tree is widely used in Europe for treating prostate disorders, but the medicinal trade has led to severe depletion of the tree where it grows in the highlands of Cameroon and other central African countries. Since fewer than 1 percent of all plant species have been screened for bioactive compounds, every loss of a unique habitat and its species is potentially a loss of future drugs and medicines. And traditional knowledge about medicinal plants is declining even faster than the plants themselves. Until recently, gene banks, botanical gardens, and protected areas have been the first line of defense in maintaining the diversity of plant life. The world's 1,600 botanical gardens, for example, collectively tend tens of thousands of plant species.