Grayson Co., VA 5/30/2009.

Grayson Co., VA 5/30/2009.

The variety found in the higher mountains (above ~3000 feet) is var. ambigua, which has slightly more deeply lobed leaves and slightly paler bark. The difference is subtle at best.

Grayson Co., VA 7/25/10.

The acorn caps of var. ambigua cover about 1/3 of the acorn, versus 1/4 for var. rubra.

Grayson Co., VA 7/25/10.

The leaves of Shumard Oak and Scarlet Oak are similar, but are glossy above and more deeply lobed. Black Oak has highly variable leaves that can look a lot like N. Red Oak, but the leaves are pubescent beneath (N. Red Oak's are smooth except for small tufts in the vein axils) and the bark is rougher and blackish.

Durham Co., NC 8/3/2003.

The leaves of saplings tend to be very shallowly lobed.

Orange Co., NC 10/15/06.

This tree is perplexing — the sinuses are much deeper than typical for Northern Red Oak. It could possibly be a hybrid with Shumard Oak.

Chapel Hill, NC 5/25/09.

The large acorns have shallow caps, covering about 1/4 of the acorn in var. rubra.

Chatham Co., NC 9/21/03.

Orange Co., NC 10/15/06.

Bark of a medium-sized tree. The trunk usually has long vertical veins of pale gray smooth bark separated by shallow furrows of rough bark (also a feature of Shumard Oak).

Bark of a large tree.

Orange Co., NC 10/15/06.

Bark of a medium-sized tree.

Granville Co., NC 4/27/08.

Bark of a large tree.

Grayson Co., VA 5/30/2009.