The reason for making this checklist public is primarily to (a) provide a listing of all cultivar and Group names known to the Registrar (hopefully so as to avoid future duplications of a known name) and (b) to enlist further comment and feedback from any interested parties prior to the publication of a full Register of oak cultivar names. It is hoped that the information here presented will be of use to a range of parties including authors, nurseries, taxonomists, oak enthusiasts and those who maintain lists of stabilized names.


The naming of cultivars and Groups is governed by the International Code of Nomenclature for Cultivated Plants (ICNCP). In these brief notes, what applies to cultivar names also applies to Group names.

A cultivar name becomes fixed upon its establishment in a printed publication. As from 1 January, 1959 such works have to be dated at least to the year. The date of a name is the publication date of that work, whether it is a book or a magazine article or even something more ephemeral such as a nursery catalogue. In a part-work or in a loose leaf binder, each loose part or sheet has to be dated at least to the year. Qualifying publications must be of the kind that are likely to be recorded in horticultural libraries. The mere placing of a name on a plant label or the communication of a name at a public meeting or show does not count as publication, nor does the placing of a name on a website or on a CD-ROM count as publication. Confidential trade lists are specifically excluded as a means of publication. (See ICNCP Arts 22–23 for further information.)

Once it can demonstrated that a cultivar name has been published, one then has to check to see that it is properly established. This means that the words of its epithet have to be in conformity with the rules of the ICNCP (Art. 19) and that after 1 January 1959, have to be in a language other than Latin and be accompanied by a description or by reference to a previously published description. A name in which the epithet is identical to, or is confusingly similar to, one that has already been published in the genus (a homonym or parahomonym) is not established. (See ICNCP Art. 24 for further information.)

Many cultivar names (especially those for woody plants) pre-date the 1959 Rule and their epithets might appear in Latin form. This is quite acceptable if the names were originally published in conformity with the International Code of Botanical Nomenclature (ICBN) and to use the terminology of that code are “validly published” (equivalent to “established” under the ICNCP). Before the advent of the ICNCP, many authors of cultivars used much older formal designations under the ranking systems provided by the ICBN. Under the rules of the ICBN, properly formed names without a description are not validly published, but under the ICNCP these might be accepted as established if they are considered to represent cultivars.

One of the prime tasks of an International Cultivar Registrar is to prove that a cultivar name has been properly established. This can be painstaking work since, in the first instance, every name seen has to be checked for the earliest known place of publication. Since the regulation of botanical nomenclature starts from 1 May 1753 (the date of Linnaeus’s Species Plantarum which started the whole system of binomial nomenclature), this means that, in theory, every work published since then has to be checked for new names. Luckily, there have always been people prepared to do this and lists of species names exist for Registrars to check. However, the systematic historical listing of what we now term cultivar names is sadly lacking (as it is generally for all names under the rank of species) and it is up to individual Registrars working within "their" plant groups to set the record straight.

There is more to this database than just a listing of cultivar names. Since so many nurseries, especially in the USA, market oaks under a common name rather than their scientific name, a listing of common names in the English language, cross-referenced to their scientific names is included. Be warned! A number of common names are applied to more than one scientific name.

Again, since a number of cultivars are marketed under the wrong scientific name, the database also includes a comprehensive list of over 1,500 correct Latin names (with their spellings verified) for all species and hybrid species (including their respective infraspecific taxa) of oak. Synonyms commonly used in the horticultural literature since the 1950s are cross-referenced to the currently accepted names. Please note that the overall synonymy is not supposed to be complete and it does not include long-forgotten or obscure names (which may, and probably should, stay forgotten or obscure!).


A full name report for a cultivar gives the full scientific name of the cultivar including any Group designation that might be given. A name that is in bold face indicates that it is properly established according to the rules of the ICNCP and that it is not considered to be a synonym. This is followed by the name of the author (in abbreviated form) who first published the cultivar epithet along with details of where the epithet was first published (book and serial names again abbreviated) and the date of publication of the name by year. If the epithet originally appeared as part of a different name or with a different spelling, this will then be given within double quotation marks in the form in which the original author presented the name. A short comment may then appear on the status of a name, viz: nom. cons. — nomen conservandum (a name that has been conserved over another, usually to save a widely used name from becoming a synonym); nom. illegit. — nomen illegitimum (one that is either a later homonym or that was superfluous when published); nom. ined. — nomen ineditum (one that does not appear to have been properly published); nom. non ratum (one that is not established under the rules of the ICNCP); nom. non rite publ. — nomen non rite publicatum (one that is not validly published under the rules of the ICBN); nom. rejic.- nomen rejiciendum (one that has been explicitly rejected in favour of another); orth. var. — orthographia varia (an orthographical variant of an accepted spelling); pro sp. (indicating that a cultivar name was first published as a species name). If the ICRA sign appears at the end of the line, this indicates that the cultivar name is accepted in this work as being registered. A report on a trademark will point one towards an accepted cultivar or Group name where further details may be found.

A full name report for a species, hybrid, or other botanical name will show the author and date of a name with a few other details concerning validity as noted above. A full name report for a common name will point towards the scientific name(s) of a taxon.

Other sets of information may appear in a full name report under the following headings:

Infrageneric Classification (species and hybrid names only). The genus Quercus is divided into two subgenera, Quercus and Cerris. Subgenus Quercus is further subdivided into five sections: Quercus (the White Oaks), Ponticae, Virentes, Lobatae (the Red Oaks), and Protobalanus (the Intermediate Oaks). Subgenus Cerris is subdivided into three sections: Cyclobalanopsis, Cerris, and Ilex.

Parentage of hybrids (nothospecies) states the names of the supposed pollen and seed parents in alphabetical order.

Common Names in this Database (species and hybrid names only) lists the common and vernacular names by which the taxon is often referred to. These names are presently in English (including transcriptions from Japanese): it is planned to add common names in other prime languages in due course.

Infraspecific Taxa Accepted in this Database (species and hybrid names only) lists the subspecies and varietas recognized within the database. Note: names of taxa below the rank of varietas are not recognized within the database — these are regarded as a minor part of the natural variation within a particular taxon

Nomenclature Note will give brief details as to the reason why a name is not accepted and if the reason is because it is contrary to a Code rule, a reference to the Code and Article in question is given. In addition, any basionym of a specific or infraspecific name is provided within this note.

History (cultivar names only) gives an account of the origins of the cultivar along with details of any raiser or introducer where this is known.

Description (cultivar name) gives a brief description or diagnosis of the cultivar or refers one to where a full description may be found. Please note that both the history and description notes have yet to be written up for many of the cultivars. For species and hybrid names a reference to a modern flora is often provided to which one may refer for descriptive information.

Natural Distribution (species names only) gives an idea of where a naturally occurring taxon may be found. It is planned to expand this information in time.

Conservation Status (species names only) shows the category in which the taxon is currently placed in the Red List of Oaks.

Nomenclatural Standard (cultivar names only) indicates the herbarium specimen, illustration, or other documentation to which the name is permanently attached.

Standard Image (cultivar names only) shows a thumbnail image of a nomenclatural standard which may be enlarged by clicking on it.

Nomenclatural Type or other Herbarium Specimen shows a thumbnail image of either a type specimen or another specimen that illustrates the taxon.

Online Herbarium Specimen provides a link through a new window to an outside website where an image of a specimen may be seen.

Illustration of Leaves shows a thumbnail image of an image in the collection of images created by Jan De Langhe, dendrologist at the Ghent University Botanical Garden, in collaboration with Arboretum Wespelaar. More of these pictures here.

Synonyms in this Database lists the names (together with their author and date) which are placed in the synonymy of an accepted name. Clicking on such a name will lead you to the full name report on the synonym.

Hybrids in this Database (under a species name) gives a listing of hybrid names and formulae known to be associated with this taxon. Clicking on the hybrid name or formula will lead you to a full name report.

Main Horticultural References lists the core horticultural works and page references in which further information may be found. Clicking on the short title of a particular work will provide a full bibliographic reference for the work in question.

Recent Monograph References will similarly identify a recent work on oaks that may contain useful information. Unfortunately, there are too few such works at present (hint for someone to write a new and complete monograph on oaks!).

Various icon buttons may appear at the bottom of a page which may guide one to further information on other web servers. The Registrar cannot be held to account if data found via these buttons is wrong or misleading.

History of the Database

The International Oak Society (IOS) was formally appointed International Cultivar Registration Authority (ICRA) in 1998 by the overseeing body, the Commission for Nomenclature and Cultivar Registration of the International Society for Horticultural Science.

Piers Trehane (1950–2011) was its first registrar. He devoted considerable time and energy to this activity. He presented a first paper at the 4th International Oak Society Conference in Winchester in 2003, introducing the Cultivar Name Registration Form. He traveled extensively over the years to collect cultivar specimens, new or old, and document them properly. In 2005, he started to work on a database with the intention to make it available online. The database was formally launched online in 2007. He presented it initially as a checklist of cultivar names, but it is much more than that, as explained above and as any user of this website will see. After his sudden death in 2011, Piers was succeeded by Ryan Russell and Eike Jablonski as registrars, supported by the members of the IOS Taxonomy Committee.

Trehane, Piers. 2004. Naming Oak Cultivars: Introducing the Cultivar Name Registration Form. Proceedings, Fourth International Oak Conference, International Oaks, No. 15, pages 126–139.

Trehane, Piers. 2007. A New Service for Quercophiles! The Oak Names Database is Now Searchable Online. Oak News & Notes, The Newsletter of the International Oak Society, Vol. 11, N° 2, page 1.


A work of this sort is never finished. There is always more information about a cultivar to discover and the database will be added to from time to time. If you know of anything that might help complete the picture, please get in contact with the Registrar (through the feedback button at the top of a page). Of particular value would be information on printed publication of any name listed with the comment "further information required".