It is still imperative to preserve the ecosystems that produce these valuable plants. Silphium, which was probably a species of giant fennel, was used as a contraceptive in the ancient world. It occurred in Cyrene, a Greek city-state on the coast of what is now western Libya. B.C. First- century Roman and Greek writers talk about silphium's being either very rare or extinct in their time. The population couldn't sustain overharvest, however, and ancient attempts to cultivate the plant were unsuccessful.
Today there is no trace of silphium.
Tests on several modern species of the same genus, however, indicate some contraceptive activity in animals, so it looks like ancient medicine wasn't far from the mark. Beyond efforts to conserve plants in their natural habitats, there are some groups that are working to save seeds from plants that scientists believe to be in immediate danger of extinction. The idea is that, if the plant goes extinct, there may be an opportunity to bring it back in the future by working from frozen genetic material. But there is no specific seed bank devoted to the preservation of medicinal plants as such. Experts do focus on medicinal plant conservation through various symposia, conferences, and publications, and there is a lot of attention focused on protecting endangered plants worldwide.