Bark turning gray to brown and scaly with age eastern hophornbeam 29 . Bark bluish gray, tight, thin and smooth with a muscular appearance American hornbeam 29. Bark ash-gray to brownish gray and furrowed see Elms 30 . Leaves star-shaped or nearly so 31 30. There are two broad groups of oaks, white oaks and red oaks.
White oaks have leaves with rounded lobes and no bristle at the ends.
Red oaks usually have leaves with small bristle at the ends of the lobes and the leaf apex. Although it is sometimes difficult to see the bristle-tips on the leaves, water oak and willow oak belong to the red oak group. Leaf undersurfaces smooth, without hairs water oak 9. Trees found on dry upland sites 12 11. Hickories Hickories are divided into two broad groups, true hickories and pecan hickories.