Introduction

Quercus ellipsoidalis E.J.Hill, Hill’s oak or northern pin oak, is an endemic of the western Great Lakes region that is sister to Q. coccinea Münchh. (scarlet oak). The species is characterized in its range by its deeply lobed leaves with C-shaped sinuses; terminal buds that are silky-pubescent on the upper 1/3 to 2/3; and acorns that are highly variable in shape and size, but with scales on the outer surface of the cap imbricate (not loose at the tips) and the inner surface of the cap smooth to moderately pubescent. The taxonomy of the species has long been contentious, as the morphological range of the species overlaps with that of Q. coccinea. However, ongoing genetic work strongly suggests that Q. coccinea is not naturalized in the upper Great Lakes region with the possible exception of isolated populations in northern Indiana and a population in southern Cook County, Illinois.

[From Hipp and Weber 2008]