Cheyenne County Conservation District

Description:
Bur oak is a large, deciduous tree with a very wide, open crown. Usually wider than tall, the tree can exceed 100 ft. in height and width. The massive trunk supports heavy, horizontal limbs and rough, deep-ridged bark. Leaves up to 9 inches long with a central midrib from which branch veins lead into rounded lobes. Lobes separated by deep sinuses reaching, in some cases, to within 1/2 inch of the midrib. Lobes beyond the midpoint of the blade wavy margined and longer and broader than those toward the base. Acorns large, up to 1 1/2 inches broad with 1/4 to more than 1/2 of the acorn enclosed in the cup. Cup with coarse scales and a fringed margin.

The acorns of this species, distinguished by very deep fringed cups, are the largest of all native oaks. The common name (sometimes spelled Burr) describes the cup of the acorn, which slightly resembles the spiny bur of a chestnut. Bur Oak is the northernmost New World oak. In the West, it is a pioneer tree, bordering and invading the prairie grassland. Planted for shade, ornament, and shelter belts. Bur oak extends farther north than any other oak species and becomes shrubby at the northern and eastern limits of its range.