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Nomenclatural standards and types

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Nomenclatural standards

A nomenclatural standard is the specimen or image that forms the definitive reference to interpret the name of a cultivar. As the RHS Herbarium specialises in plants of garden value, more especially cultivars, there is an active programme of acquiring standard specimens.

Currently, the RHS Herbarium has nearly 5,000 nomenclatural standards.

Download a list of nomenclatural standards (Adobe Acrobat pdf)

What is a nomenclatural standard?

Example of a nomenclatural standardAbove is an example of the standard portfolio for Lavandula angustifolia Mill. ‘Hidcote’. In this example the nomenclatural standard takes the form of a herbarium specimen. A description is attached to the specimen, which includes the colour of the floral features using the RHS Colour Chart. Part of the standard portfolio includes a photographic transparency showing the habit, form and colour, details frequently lost in pressing.

The first place of publication is a vital piece of information for interpreting the cultivar; in this instance it is Carlile’s Hardy Plants nursery catalogue of 1953.

Supporting documentation for this portfolio comes from the RHS Trials Bulletin of Lavender and a recent monograph on the genus. Such a standard portfolio provides a vital resource for botanists and researchers.

Type specimens

Type specimens provide a permanent reference point to determine the correct application of scientific plant names. Under the rules laid out by the International Code of Botanical Nomenclature each name at the rank of species or below must have a type specimen attached to it. The herbarium also has a number of type specimens.

View the list of type specimens (Adobe Acrobat pdf)

Interested in nomenclature?


You may interested in Hanburyana, the yearly publication from the RHS Botany department. It is available online.

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