Titan arum, the corpse flower, a distinctive plant at risk of extinction. A new study identifies thousands of flowering plants belonging to rare and ancient lineages that are in urgent need of protection.  These research focuses on species with few surviving relatives, such as the ginkgo tree , which is believed to be the last remaining member of a line that goes back more than 300 million years. The ginkgo occupies a long and isolated branch of the tree of life. If it were to go extinct, scientists say, a significant part of evolutionary history would be lost.  For the research, scientists evaluated each species of flowering plant — of which there are more than 330,000 — to determine its distinctiveness and its risk of extinction. For plants that had not been formally assessed, they used computer modeling to determine its level of vulnerability. From this, scientists determined that more than 20 percent of the evolutionary history of flowering plants is at risk of being eradicated.…