All are trees or shrubs bearing acorn-like fruit in which a cup covers at least the base of the nut.

The outer structure of the mature pollen is one feature that distinguishes the two subgenera: in subgenus Quercus, the small folds or wrinkles (rugulae) are obscured by sporopollenin, whereas in subgenus Cerris, the rugulae are visible or at most weakly obscured.

[2] The following cladogram summarizes the relationships that Denk et al. used to draw up their 2017 classification:[2] sect.

[3] The section, or part of it, has also been treated under names including Quercus sect.

The 'cup' (cupule) of the acorn is fused with its stalk (peduncule) forming a connective piece.

Both the connective piece and the cup are covered with small triangular scales, mostly thin and membranous with broadly angled tips.

Protobalanus was first established as a subgenus by William Trelease in 1922 and then later treated as a section by Otto Karl Anton Schwarz in 1936 and Aimée Antoinette Camus in 1938.

The scales are thick and compressed into rings, often forming small bumps, that may be obscured by glandular hairs.

[2] The section contains only five species, native to southwestern North America and northwestern Mexico.

The cup (cupule) at the base of the acorn has scales with sharp angled ends.

The leaf buds are large, enclosed in loosely attached scales.

Quercus pontica is native to mountainous areas of north-eastern Turkey and western Georgia.

Quercus sadleriana is native to northern-most California and southern-most Oregon in the United States.

The cup at the base of the acorn has narrowly triangular scales, with thin keels, at most small bumps (tubercules), and sharp angled ends.

The section includes all white oaks from North America (treated by Trelease as subgenus Leucobalanus).