The genus Quercus contains about 500 known species, plus about 180 hybrids between them. The genus, as is the case with many large genera, is divided into subgenera and sections. Traditionally, the genus Quercus was divided into the two subgenera Cyclobalanopsis, the ring-cupped oaks, and Quercus, which included all the other sections. However, a comprehensive revision in 2017 identified different relationships. Now the genus is commonly divided into a subgenus Quercus and a subgenus Cerris, with Cyclobalanopsis included in the latter. The sections of subgenus Quercus are mostly native to the New World, with the notable exception of the white oaks of sect. Quercus and the endemic Quercus pontica. In contrast, the sections of the subgenus Cerris are exclusively native to the Old World.

Unless otherwise indicated, the lists which follow contain all the species accepted by Plants of the World Online , plus selected hybrids that are also accepted, with placement into sections based on a list produced by Denk et al. for their 2017 classification of the genus.

Legend Species with evergreen foliage ("live oaks") are tagged '#'. Species in the genus have been recategorized between deciduous and evergreen on numerous occasions, although this does not necessarily mean that species in the two groups are closely related.

Subgenus Quercus

Section Quercus

Section Mesobalanus was included in section Quercus in the 2017 classification used here. Other synonyms include Q. sect. Albae and Q. sect. Macrocarpae. The section comprises the white oaks from Europe, Asia, north Africa, Central and North America. Styles short; acorns mature in 6 months, sweet or slightly bitter, inside of acorn shell hairless.

Quercus aculcingensis Trel. – Mexico Quercus ajoensis C.H.Mull. – Ajo Mountain shrub oak, Blue shrub oak – Arizona, New Mexico, Baja California Quercus alba L. – white oak – eastern and central North America Quercus aliena Blume – Oriental white oak – eastern Asia Quercus alpescens Trel. – Mexico Quercus ariifolia Trel. – Mexico (Sierra Madre Oriental) Quercus arizonica Sarg. – Arizona white oak – # southwestern U.S., northwestern Mexico Quercus aurea – southeastern and south-central Europe Quercus austrina Small – bluff oak – southeastern North America Quercus barrancana – Mexico (Chihuahua) Quercus × basaseachicensis C.H.Mull. – Mexico (Chihuahua, Durango) Quercus × bebbiana C.K.Schneid. — Bebb's oak — northeastern North America Quercus berberidifolia Liebm. – California scrub oak – # California Quercus bicolor Willd. – swamp white oak – eastern and midwestern North America Quercus × bimundorum E.J.Palmer - two worlds oak - U.S. Quercus boyntonii Beadle – Boynton's post oak – south central North America Quercus canariensis Willd. – Mirbeck's oak or Algerian oak – # North Africa & Spain Quercus carmenensis C.H.Mull. – Carmen oak – Coahuila and Texas Quercus centenaria – southwestern Mexico (Jalisco and Nayarit) Quercus × cerrioides Willk. & Costa – east Spain Quercus chapmanii Sarg. – Chapman oak – # southeastern U.S. Quercus chartacea Trel. – Southern Mexico Quercus chihuahuensis Trel. – Chihuahua oak – northern Mexico and Texas Quercus congesta C.Presl – Italy Quercus convallata Trel. – Mexico Quercus copeyensis C.H.Mull. – # Costa Rica, Panama Quercus cornelius-mulleri Nixon & K.P.Steele – Muller oak – # southwestern North America Quercus corrugata Hook. – Mexico, Central America Quercus dalechampii Ten. – southeastern Europe Quercus deliquescens C.H.Mull. – Mexico Quercus dentata Thunb. – daimyo oak – eastern Asia Quercus depressipes Trel. – Davis Mountain oak – northern Mexico and Texas Quercus deserticola Trel. – # Mexico Quercus diversifolia Née – Mexico Quercus douglasii Hook. & Arn. – blue oak – California Quercus dumosa Nutt. – coastal scrub oak – # southern California, Baja California, Arizona Quercus durata Jeps. – leather oak – # California Quercus edwardsiae C.H.Mull. – Mexico Quercus engelmannii Greene – Engelmann oak – # southern California, Baja California Quercus estremadurensis O.Schwarz – Portugal, Spain, Morocco Quercus fabri Hance – Faber's oak – central to southern China Quercus faginea Lam. – Portuguese oak – # southwestern Europe Quercus frainetto Ten. — Hungarian oak — southeastern Europe Quercus frutex Trel. – Mexico †Quercus furuhjelmi — Eocene to Miocene - Alaska, Kazakhstan Quercus gambelii Nutt. – Gambel oak – southwestern North America Quercus garryana Douglas ex Hook. – Oregon white oak or Garry oak – western North America Quercus germana Schltdl. & Cham. – Mexico Quercus glabrescens Benth. – Mexico Quercus glaucescens Bonpl. – encino blanco – Mexico Quercus glaucoides M.Martens & Galeotti – # Mexico Quercus greggii (A.DC.) Trel. – # Mexico Quercus griffithii Hook.f. & Thomson ex Miq. – southeast Asia Quercus grisea Liebm. – gray oak – # southwestern North America Quercus hartwissiana Steven – Strandzha oak – southeastern Bulgaria, northern Turkey, western Georgia, southwestern Russia Quercus havardii Rydb. – Havard oak, shinnery oak, shin oak – south central North America †Quercus hiholensis — Miocene — # Washington State Quercus hinckleyi C.H.Mull. – Hinckley oak – # Texas, northwestern Mexico Quercus ichnusae Mossa, Bacch. & Brullo – Sardinia Quercus infectoria G.Olivier – Aleppo oak, Cyprus oak – southern Europe, southwestern Asia Quercus insignis M.Martens & Galeotti – Mexico, Belize, Costa Rica, Guatemala, Panama Quercus intricata Trel. – Coahuila scrub oak – # two isolated localities in west Texas, northern Mexico Quercus invaginata Trel. – Mexico Quercus john-tuckeri Nixon & C.H.Mull. – Tucker's oak – California Quercus juergensenii Liebm. – Mexico Quercus kotschyana O.Schwarz – Lebanon Quercus laceyi Small – lacey oak – Edwards Plateau of Texas, northern Mexico Quercus laeta Liebm. – Mexico Quercus lancifolia Schltdl. & Cham. – southwestern North America, Mexico, South America Quercus liebmannii Oerst. ex Trel. — Mexico Quercus lobata Née – valley oak or California white oak – California Quercus lusitanica Lam. – gall oak or Lusitanian oak – Iberia, North Africa Quercus lyrata Walter – overcup oak – eastern North America Quercus × macdonaldii Greene & Kellogg – California Quercus macdougallii Martínez – Mexico Quercus macranthera Fisch. & C.A.Mey. ex Hohen. – Caucasian oak or Persian oak – western Asia Quercus macrocarpa Michx. – bur oak – eastern and central North America Quercus magnoliifolia Née – Mexico Quercus manzanillana Trel. – Mexico Quercus margarettae (also Q. margaretiae and Q. margarettiae) — sand post oak — southeastern North America Quercus martinezii C.H.Mull. – # Mexico Quercus melissae – Mexico (Chiapas) and Guatemala Quercus michauxii Nutt. – swamp chestnut oak – eastern North America Quercus microphylla Née – Mexico Quercus mohriana Buckley ex Rydb. – Mohr oak – # southwestern North America Quercus mongolica Fisch. ex Ledeb. – Mongolian oak – eastern Asia Quercus monnula Y.C.Hsu & H.Wei Jen – south-central China Quercus montana Willd. – chestnut oak – eastern North America (= Quercus prinus) Quercus muehlenbergii Engelm. – Chinkapin oak – eastern, central, and southwestern US (West Texas and New Mexico), northern Mexico Quercus neoplatyphylla – central and southwestern Mexico Quercus ningqiangensis S.Z.Qu & W.H.Zhang – southeastern China Quercus oblongifolia Torr. – Arizona blue oak, Southwestern blue oak, or Mexican blue oak – # southwestern U.S., northwestern Mexico Quercus obtusata Bonpl. – Mexico Quercus oglethorpensis W.H.Duncan – Oglethorpe oak – southeastern North America Quercus oocarpa Liebm. – Mexico Quercus opaca Trel. – Mexico Quercus pacifica Nixon & C.H.Mull. – # Channel Islands, California Quercus pauciradiata – Spain Quercus peduncularis Née – # Central America Quercus perpallida Trel. – Mexico Quercus petraea (Matt.) Liebl. – sessile oak, durmast oak – Europe, Anatolia Quercus petraea subsp. polycarpa (Schur) Soó - Georgian oak - Austria to Iran and the Caucasus Quercus petraea subsp. pinnatiloba (K.Koch) Menitsky - Lebanon-Syria, Turkey, South Caucasus Quercus polymorpha Schltdl. & Cham. – Monterrey oak, Mexican white oak – # Mexico and extreme S. Texas Quercus porphyrogenita Trel. – Mexico Quercus potosina Trel. – Mexico Quercus praeco Trel. – Mexico Quercus pringlei Seemen ex Loes. – Mexico Quercus prinoides Willd. – dwarf chinkapin oak – eastern North America Quercus pubescens Willd. – downy oak or Italian oak – Europe, Anatolia Quercus pungens Liebm. – sandpaper oak or pungens oak – southwestern U.S., Mexico Quercus purhepecha – Mexico (Michoacán) Quercus purulhana Trel. – Mexico, Central America Quercus pyrenaica Willd. – Pyrenean oak – southwestern Europe Quercus rekonis Trel. – Mexico Quercus repanda Bonpl. – Mexico Quercus resinosa Liebm. – Mexico Quercus robur L. – pedunculate oak, English oak or French oak – Europe, West Asia Quercus rugosa Née – netleaf oak or Rugosa oak – # southwestern U.S., northwestern Mexico Quercus sanchez-colinii – Mexico Quercus × schuettei Trel. — Schuette's oak — US, Canada Quercus sebifera Trel. – # Mexico Quercus segoviensis Liebm. – Mexico and northern Central America Quercus serrata Murray – bao li – # China, Taiwan, Japan, Korea Quercus shennongii C.C.Huang & S.H.Fu – southeastern China Quercus shingjenensis Y.T.Chang – China (Guizhou) Quercus similis Ashe – swamp post oak – southeastern North America Quercus sinuata Walter – bastard oak – southern US (formerly identified as Quercus durandii) Quercus sororia Liebm. – Mexico Quercus stellata Wangenh. – post oak – eastern North America Quercus striatula Trel. – Mexico (Sierra Madre Occidental and Mexican Plateau ranges) Quercus subspathulata Trel. – Mexico Quercus supranitida C.H.Mull. – Mexico Quercus tinkhamii C.H.Mull. — Mexico Quercus toumeyi Sarg. — Toumey oak — # southwest New Mexico, southeastern Arizona, northern Mexico Quercus toxicodendrifolia – eastern and southeastern Mexico Quercus tsinglingensis – southeastern China Quercus tuberculata Liebm. — Mexico Quercus turbinella Greene — turbinella oak, Arizona Blue Shrub oak, Shrub live oak or scrub live oak — # southwestern North America Quercus vallicola – central Mexico Quercus vaseyana Buckley — Vasey oak — # southwestern North America Quercus verde C.H.Mull. — Mexico Quercus vicentensis Trel. — El Salvador, Guatemala, and southern Mexico Quercus vulcanica Boiss. & Heldr. ex Kotschy — Kasnak oak — southwestern Asia Quercus welshii R.A.Denham — havard oak, Utah sand oak, wavy leaf oak — # southwestern North America Quercus wutaishanica Mayr — Liaoning oak — China, Mongolia Quercus xylina Scheidw. — Mexico

Section Ponticae

Species are native to Western Asia and Western North America. They produce catkins up to 10cm long; the acorns mature annually.

Quercus pontica — Pontine oak — western Asia Quercus sadleriana — deer oak — # southwestern Oregon, northern California

Section Protobalanus

The intermediate oaks. Southwest USA and northwest Mexico. Styles short, acorns mature in 18 months, very bitter, inside of acorn shell woolly.

Quercus cedrosensis — Cedros Island oak — # California, Baja California Quercus chrysolepis — canyon live oak — # southwestern North America Quercus palmeri — Palmer oak — # California, western Arizona Quercus tomentella — island oak — # Channel Islands of California, Baja California (Guadalupe Island) Quercus vacciniifolia — huckleberry oak — # southwestern North America

Section Lobatae

The red oaks (synonym sect. Erythrobalanus), native to North, Central and South America. Styles long, acorns mature in 18 months (in most species),Kershner, Bruce, and Craig Tufts. National Wildlife Federation Field Guide to Trees of North America. New York: Sterling Pub., 2008. Print. very bitter, inside of acorn shell woolly.

Quercus acatenangensis Trel. – Mexico, Guatemala, El Salvador Quercus acerifolia (E.J.Palmer) Stoynoff & W.J.Hess ex R.J.Jensen – maple-leaved oak or mapleleaf oak – Arkansas