M B Bayer, PO B0x 960, 7579 Kuilsriver, RSA.
Taxonomy is simply classification of living or once-living organisms into supposed natural units that are basic to the organization of life forms and which are called species. Classification itself is a process of organizing objects or ideas of any kind into functional groups to serve some general or specific purpose. Therefore the classification of plants in a group like Haworthia is subject to a number of stresses.
Primarily the idea should be that the classification serves a botanical and hence scientific purpose that indicates the past, present and even future of every plant of Haworthia in relation to all the others of the same general kind, as well as to other plants and other living organisms. An obstacle to this ideal is that the concept of the species is not defined any better than the broad zoological acceptance of a species being a group or groups of interbreeding or potentially interbreeding individuals. This definition simply does not hold for plants and there are many reasons why not. Furthermore it is not certain that the process of Darwinian selection and slow change by random mutation is how change is actually driven. Thus from the scientific point of view it is almost impossible to assess a classification without a very broad and inclusive overview of the plant world and the consideration that the taxonomist demonstrates for the variables and possibilities that exist. To do this requires a level of knowledge, expertise and experience, not only of biology in general, but also of the group of plants viz. Haworthia under consideration.
Secondarily a classification serves the need of a user group outside of science and this can be the casual observer, the naturalist, the enthusiast and the collector/grower. The casual observer generally will make no demands on a classification provided the classification is approximately true and appears to be accepted in the formal ranks. The naturalist is a bit more difficult to please because the formal ranks are known to be questionable. The enthusiast and grower are still more difficult to satisfy because unlike the naturalist, there is a greater need for accuracy and precision of identification and application of any name.
How then can one hope to bring the two ideals of classification together to serve one common purpose? The truth, so vividly demonstrated in the history of the literature of Haworthia, is that it cannot be done unless there is a dramatic turnabout from the two user groups. The scientific community needs firstly to get its act together and recognize the flaws and weaknesses that are incipient in the mainstream scientific literature. Then the user group needs to exercise better discrimination and recognize that any opinion is only as good as the information and truths on which it rests.