Catalina mahogany (Cercocarpus traskiae)
This small tree is endemic to Catalina Island with only one single population remaining in the wild, according to IUCN, which lists the Catalina mahogany tree as critically endangered. About seven individual trees remain of a species that the Catalina Island Conservancy calls one of the rarest in the U.S.
But conservation efforts have momentum, the conservancy says. Researchers found that this plant was not successfully reproducing, so the island fenced in the plants to protect them from hungry animals. And each summer, biologists assess the trees' health, look for fungus or insect damage, track growth patterns and measure fruit production.