A note on the Nomenclature of Wisteria
As with all commercially available cultivars of plants, Wisteria has suffered many mis-labellings over the years, resulting in many synonyms and not a little confusion.
Since Peter Valder’s book Wisteria – A Comprehensive Guide, published in 1995, which has generally been accepted as the definitive nomenclature guide for the last twenty odd years, much research has been done into the nomenclature of Wisteria, including DNA research both here in the UK and in Belgium, and some changes have been made in 2016 that will be integrated into the RHS Plant Finder.
All the names I have used in the collection are under this new nomenclature, and this is a brief explanation as to the changes.
Changes to the Japanese species of Wisteria
- x valderi ‘Murasaki-Kapitan’ was originally included in the species W. brachybotrys as W. brachybotrys ‘Murasaki-Kapitan’ but is now recognized as a hybrid. It twines clockwise instead of anticlockwise as in all the other brachybotrys cultivars.
- x valderi ‘Eranthema’ was originally named W. floribunda ‘Eranthema’, and is also recognized as a hybrid.
Both the above have been named in recognition of Valder’s work.
The biggest issue has been with the species W. floribunda and the especially long racemed cultivar known previously as either W. floribunda ‘Macrobotrys’ or W. ‘Multijuga’, and thought to be synonyms for the same plant.
The plant now known as W. floribunda f multijuga was named as W. floribunda ‘Macrobotrys’ in Valder’s book, but multijuga is now recognized as a forma of floribunda.
Similarly, there is now a Macrobotrys Group within the species W. floribunda which includes the plants W. floribunda Macrobotrys Group ‘Hocker Edge’ and W. floribunda Macrobotrys Group ‘Burford’ (previously classified as W. floribunda ‘Hocker Edge’ and W. x ‘Burford’).
The Macrobotrys Group are characterized botanically by the very large calyx teeth.
Changes to the North American species of Wisteria
Previously, there were two recognized species, W. frutescens and W. macrostachya, but as a result of recent DNA studies, the modern classification is one species only, W. frutescens, with macrostachya as a variation within that species.
So, a plant which was W. macrostachya ‘Aunt Dee’ is now known as W. frutescens var. macrostachya ‘Aunt Dee’.
I would like to thank Dr James Compton for his clarification on this and sending me the articles he has written in Curtis’s Botanical Magazine on the subject.