International Cultivar Name Registration

Cultivar Name Registration at the U.S. National Arboretum

The U.S. National Arboretum presently serves as the International Cultivar Registration Authority (ICRA) for two genera, Cercis (since 2013) and Lagerstroemia (since 1970). Since March 2013, under the auspices of the American Public Gardens Association, it has also conducted cultivar name registrations for the ICRA for Unassigned Woody Genera, which includes more than 1,000 genera of primarily woody plants. The international cultivar name registration system is administered by the International Society for Horticultural Science (ISHS), and cultivar names are governed by the International Code of Nomenclature for Cultivated Plants (ICNCP).

The U.S. National Arboretum has been active in registering cultivars of various single genera of ornamental plants since 1958, when it was appointed as the International Cultivar Registration Authority (ICRA) for Viburnum, with Dr Donald Egolf as registrar. Later, the Arboretum also became the assigned ICRA for Pyracantha (1966), Lagerstroemia (1970), and Cercis (2013). Of these, Viburnum and Pyracantha were ultimately relinquished to the ICRA for Unassigned Woody Genera (in approximately 2013 and 1998, respectively). Cultivar checklists have been completed for Pyracantha (published 1995; see: A Checklist of Pyracantha Cultivars [external link to Biodiversity Heritage Library]), for Lagerstroemia (online; link coming soon), and for Cercis.

The Arboretum has also served twice as registration authority for the ICRA for Unassigned Woody Genera for the American Public Gardens Association (formerly the American Association of Botanical Gardens and Arboreta): first from 1981 until September 1983 with Dr Theodore “Ted” Dudley as registrar, and again from March 2013 until the present, with Stefan Lura as registrar. Under this authority, cultivars registrations in over 1,000 genera of primarily woody taxa not otherwise covered by other ICRAs may be registered. For an official listing of these genera, see: (external link).

Within each ICRA, an individual typically serves as International Registrar and primary point of contact for those seeking registration. For registrations of Cercis and Lagerstroemia, David Kidwell-Slak ( serves as international registrar. For cultivars governed by the ICRA for Unassigned Woody Genera, the registrar is Stefan Lura (

For more information about the ICRA program, please see the ISHS web site at There you will find a complete list of genera that are served by ICRAs, including those of the ICRA for Unassigned Woody Genera.

A cultivar name may be established at any time through publication of the name, along with a validating description, in one of several forms of media sanctioned by the ICNCP, such as a dated nursery catalog, journal article, or book. The name must adhere to the various rules outlined the ICNCP in order to be considered valid, and it is especially important to avoid the duplication of cultivar names within the denomination class (usually the genus). Registration is an additional, complementary process that is designed to help ensure that each cultivar epithet (names) is valid according to all of the terms of the ICNCP. ICRAs also maintain lists of existing cultivar registrations and information about those cultivars, and they develop and maintain official checklists for specific denomination classes (usually genera).

Cultivar registration at the Arboretum is performed free of cost, and helps to ensure that new cultivar epithets (names) comply with the International Code of Nomenclature for Cultivated Plants. For further instructions on submitting a registration request, see the appropriate registration page for details:

Checklist and International Registration of Cercis Cultivars

Checklist and International Registration of Lagerstroemia Cultivars

International Registration of Cultivars of Unassigned Woody Genera (coming soon)