Florida yew (Taxus floridana)
There's only one known tiny population of this critically endangered tree species: a 9-square-mile section of ravines and bluffs along the Apalachicola River in in northern Florida. A lack of regeneration, an increasing deer population and declining habitat quality are the main culprits for the dwindling number of plants, according to the IUCN Red List.
The United States Botanic Garden, which calls the Florida yew one of the rarest trees in the world, says another reason the trees are endangered is because many are on private land, and endangered species laws do not protect endangered plants on private property.
The botanic garden uses the Florida yew to show why conserving these trees is so important. The bark on this species of yew contains the cancer-fighting compound taxol, which has proven useful in treating breast cancer, ovarian cancer, some kinds of leukemia and certain kidney diseases.