PSC 2620: Woody Trees and ShrubCourse HomeWeek 5

Quercus macrocarpa - Bur or Mossycup Oak

Plant Viewer
The leaf is obovate with very irregular rounded lobes. Unlike Quercus robur the lobes are not paired. 1/2 to 1 inch, elongated acorns form during the summer and ripen in the fall. They often appear in clusters on the tree. Image: NRCS

Plant Description

Quercus macrocarpa, or Burr Oak, is an oak species native to the United States. It is one of the most cold tolerant Oaks, hardy to zone 3. It grows to be 50-70 feet tall with a similar or wider spread. It is highly tolerant of poor soils and drought conditions, but can be difficult to establish due to its long tap root that can be damaged during transplanting.

The dark gray-brown bark is very rough with deep furrows and pronounced ridges and tends to flake off. The bark forms quickly on young branches and is a distinctive feature of the tree. The leaves are large (4-10 inches long) and obovate in form. They have several pairs of round lobes that form towards the bottom of the leaf with an otherwise smooth margin. The leaf is dark green and tends to be glabrous, while the underside of the leaf is a pale grey or white color.

1 to 1 1/2 inch acorns form in the summer and ripen in the fall. The acorn is encased half way down the length of the nut or more by the involucre which has a very distinct hairy fringe at its bottom.

Landscape Use

Its size precludes its use in most modern residential landscapes, but it is an excellent choice for a shade tree on commercial or educational campuses.