WHAT'S IN A NAME?
A RHODODENDRON BY ANY OTHER NAME IS JUST AS PRETTY

Timber press has just published James Cullen latest book, Hardy Rhododendron Species-A Guide to Identification, his most recent revision of the classification of the genus Rhododendron. He has been deeply involved in this project for over 30 years, and his grasp of the relationships of the species is emerging as the definitive understanding of the genus.

Here finally is an easy to use identification key to the genus Rhododendron that results in species names that are the current standards in the genus. Priced at a reasonable $49.95, this volume is sure to become the most frequently accessed species book in any collection.

 book pic

The initial chapter gives an easy to read introduction to the evolution of the rhododendron classification system as more and more collections from the wilds become available for study. The chapter finishes with an excellent description of the characteristics that are used in rhododendron taxonomy.

The main portion of the book is taken up by a dichotomous key that steps through the entire genus to come to unique species names. As you identify each successive character, two choices are presented that narrow down the possible identification until you arrive at only a single species that matches all of the decisions made. The organization of the taxa is according to the understanding of the genus that Cullen and Chamberlain have developed over the last 30 years, and represents the most widely accepted view in the rhododendron world.

The 400 or so species of the section Vireya are specifically excluded from this work, though Maddenia hardy enough to be included. There are some 800 species that are covered in this book.

The species descriptions are succinct and easy to understand. Each characteristic is clearly set off from the others. Each attribute can rapidly be compared to the same attribute in other species. The defining characteristics of the species are given in the key as identification is developed, so no further emphasis is made in the species descriptions.

Many species are illustrated by excellent photographs of the truss, a floret, and a close-up detail of the leaf. The leaf pictures are detailed to show the variation present in scales and indumentum, making them invaluable in species identification. All the other species descriptions contain references to publications where pictures or drawings may be found. This keeps the book functional as a reference work, rather than turning it into just another coffee table book.

The book also contains a second arrangement of the genus, this time in stripped down table form. Its appearance is much less daunting than the earlier dichotomous key. Only the branching decision choices are listed. The full descriptions found in the main key are not repeated here. The result is a concise table that can rapidly be followed to the species end point.

Finally, there is a characteristics table. A specific characteristic is followed by a list of the groups and species having that characteristic. You can easily see how unique a feature is, and how useful it might be for identification. By looking up several different features and seeing which species exhibit all those characteristics, more than 800 possibilities can rapidly be reduced to a just a few alternatives.

Timber Press
ISBN 0-88192-723-6
374 pp, approx. 176 color photos
4 line drawings, 7/9 inch, hardcover
$49.95   CAN $69.96
Publication date: September 2005
 

 

I usually try to look up the most troublesome or controversial classifications in order to find out how the plant is handled in any new tome. The 1997 RHS Rhododendron Handbooklists the species groenlandicum and tomentosum in the section Rhododendron, subsection Ledum but I found no listing to these species, nor even to the subsection, in the Cullen book. Only that some people thought that they should be a part of the genus Rhododendron. I wonder where groenlandicum is growing now.

Another example is R. smithii. All of the other books list it as a synonym for R. argyrophyllum, but not this book. I wish that Cullen would have added a few notes of explanation where his classification differed noticeably from other specialists in the field.

Rhododendron classification can be a real pain. Ask any old timer. They will come up with species names that none of the current identification books list. The Rhododendron Society published The Species of Rhododendron in 1930, with a second edition in 1947, both organized along the lines of the Balfourian System. The Royal Horticultural Society published the first edition of The Rhododendron Handbook in 1980 which adhered to the Balfourian classification system, while the 1998 edition followed the Cullen & Chamberlain revisions of the genus Rhododendron while continuing to list the species alphabetically.

In the 1980s and 90s Timber Press published several other books on the classification of Rhododendrons. Peter Cox authored The Larger Rhododendronsand The Smaller Rhododendrons H. H. Davidian penned the monumental The Rhododendron Species in 4 volumes (1982-1995). The Davidian books more closely follow the relationships established under the pre-existing Balfourian system, though his treatment of individual species is thorough and detailed.

Hardy Rhododendron Species- A Guide to Identification by James Cullen is the first easy to use identification key to the genus Rhododendron that results in species names that are the current standards in the genus.

 Reviewed by Luurt G. Nieuwenhuis