Much of the early work on Haworthia was based on fairly limited observations in nature. These were essentially point collections (often very close to roads) from which seemingly discrete elements were recognised as species. This is akin to a survey made from a plane flying at low altitude assuming that broader patterns are being more easily identified at this illusory distance. The obvious danger of such incomplete observations is that simplistic or incorrect conclusions might be drawn. Indeed, the classification often seems easy from such selective sampling.
When Bruce Bayer started his studies of the genus Haworthia circa 1970, a new era of more methodical collection and thorough recording of the material resulted. Due to the enormity of the task, Bruce’s fieldwork focussed on the Worcester/Robertson Karoo, where he built up an excellent understanding of the natural variation of and complex interaction between the recognised species of the area. His resulting model was then extrapolated to lesser-known areas further east. This work culminated in the landmark publications The New Haworthia Handbook in 1982 and Haworthia Revisited in 1999, where a classification framework for understanding the genus was proposed. This framework has been extensively field-tested by a number of people, including myself, and found to be workable.
Bruce remained doubtful about some of his solutions which were based on insufficient collection data, and some new collections which were difficult to place within the framework. During the course of the past few years he has studied further some of the problem areas, the results of which are presented in this update. New insights were gained which are used to propose an improved framework, in the form of a hypothesis, for the major Eastern Cape species complexes. As Bruce points out, this is not the only possible solution as there seem to be several alternatives, each with some reservation, when attempting to explain the observed natural variation. Some problem areas in the Eastern Cape and Little Karoo warrant further detailed investigation. Nevertheless, this work presents a valuable extension of our knowledge of Haworthia.
In his foreword to The New Haworthia Handbook in 1982, Prof. H. B. Rycroft said “the wide range of species and their endless variability keep the professional taxonomist fully occupied and sometimes confused”. This account shows how local continuities exist between adjacent species, only to be contradicted by discontinuities elsewhere between the same species. It is a pleasure for me to introduce you to this fascinating story.
Foreword by the Publisher
This collection of essays deals with some of the more intractable problems in the classification of Haworthia, and demonstrates just how ambiguous types can be. It also demonstrates the scale and nature of the problem in a far clearer way than Bayer’s revision. Bayer himself has said that his revision is still probably premature, and that a lot more needs to be known about Haworthia. This up-to-date account shows where some of the difficulties lie and that it is difficult to determine discontinuities in the species of the genus. Bayer pointed out that there seemed little sense in the emphasis on, and pre-occupation with, types and names, when the elements to which they are being applied are simply misunderstood or even unknown.
The process of the classification of plants is ongoing and it is correct that work should be published before the final solution is reached, as such solutions are probably unattainable. It is therefore appropriate that Haworthia Revisited should be followed by the present series of essays. It is the intention to continue publishing further collections of essays, at present four sets are envisaged. When the first four are complete, they will be bound into “collectors” editions and made available to purchasers of the original books.