Maple-leaf oak (Quercus acerifolia)
It's name says maple but make no mistake: This is an oak tree with maple-tree-shaped leaves — a rare species that only grows in steep, rocky forests of the Ouachita Mountains (pictured) in west central Arkansas and southeast Oklahoma. It's listed as endangered on the IUCN Red List due to habitat degradation, with fewer than 600 individuals left in the wild.
Maple-leaf oak trees grow to 40 or 50 feet tall, the Missouri Botanical Garden says, and the leaves on this deciduous tree of the red oak group are yellowish-green.
Seventy-eight species of oak trees are threatened around the world, including 17 in the U.S., according to Botanic Gardens Conservation International.