White oaks

The white oaks, Quercus subgenus Quercus section Quercus, are a group of oaks distinguished by their relatively sweet acorns that mature in 6-7 months, and have a hairless inside to the acorn shell. The leaves are also commonly characterised by the absence of any small bristle at the tip of the leaf or on any lobes on the side of the leaf. They are found in Europe, Asia and North America.

Genus Quercus

• Subgenus Quercus. Typical oaks. Widespread; acorns not tightly clustered, with scales on acorn cup arranged in spirals.

• Section Quercus (synonym Lepidobalanus). The white oaks. Europe, Asia, north Africa, North America. Styles short; acorns mature in 6 months, sweet or slightly bitter, inside of acorn shell hairless.
  • Quercus alba - White oak - eastern North America
  • Quercus aliena - Oriental white oak - eastern Asia
  • Quercus arizonica - Arizona white oak # - southwestern North America
  • Quercus bicolor - Swamp white oak - eastern North America
  • Quercus douglasii - Blue oak - southwestern North America
  • Quercus emoryi - Emory oak # - southwestern North America
  • Quercus faginea - Portuguese oak - southwestern Europe
  • Quercus fusiformis - Texas live oak - south central North America
  • Quercus gambelii - Gambel oak - western North America
  • Quercus garryana - Oregon white oak - western North America
  • Quercus grisea - Gray oak - south central North America
  • Quercus havardii - Sand shinnery oak - south central North America
  • Quercus ilex - Holm oak # - southern Europe
  • Quercus lobata - Valley oak or California white oak - southwestern North America
  • Quercus lyrata - Overcup oak - eastern North America
  • Quercus macrocarpa - Bur oak - eastern North America
  • Quercus mongolica - Mongolian oak - eastern Asia
  • Quercus michauxii - Swamp chestnut oak - eastern North America
  • Quercus muehlenbergii - Chinkapin oak - eastern North America
  • Quercus oblongifolia - Mexican blue oak # - southwestern North America
  • Quercus petraea - Sessile oak - Europe
  • Quercus prinus - Chestnut oak - eastern North America
  • Quercus pubescens - Downy Oak - Europe
  • Quercus pungens - Sandpaper oak # - south central North America
  • Quercus robur - English oak - Europe
  • Quercus stellata - Post oak - eastern North America
  • Quercus turbinella - Shrub live oak # - western North America
  • Quercus virginiana - Southern live oak # - southeastern North America

• Section Mesobalanus. Europe, Asia, north Africa. Styles long; acorns mature in 6 months, bitter, inside of acorn shell hairless (closely related to sect. Quercus and sometimes included in it).

• Section Cerris. Europe, Asia, north Africa. Styles long; acorns mature in 18 months, very bitter, inside of acorn shell hairless or slightly hairy.

• Section Protobalanus. Southwest USA & northwest Mexico. Styles short, acorns mature in 18 months, very bitter, inside of acorn shell woolly.

• Section Lobatae (synonym Erythrobalanus). The red oaks. North, Central & South America. Styles long, acorns mature in 18 months, very bitter, inside of acorn shell woolly.

• Subgenus Cyclobalanopsis. Cluster-acorn oaks. A large group of evergreen oaks in east Asia with clustered acorns and the scales on the acorn cups in distinct concrescent rings (see photo, top right on the Quercus main page); often treated as a separate genus Cyclobalanopsis.

Species with evergreen foliage are tagged #. Note that evergreen character has evolved on numerous occasions in Quercus, and does not necessarily indicate that the species concerned are closely related.

For the other sections, see List of Quercus species.