Introduction

The systematic and taxonomical history of the genus Coryphantha, like that of many other genera of Cactaceae, is characterised by a great number of multiple descriptions and innumerable, sometimes confusing, nomen-clatural changes and many errors.

The first uncertainties were introduced by the incomplete and imprecise descriptions made by early botanists and non-botanist plant collectors. Many of their first descriptions were published in non-professional journals or journals of limited distribution. In consequence, later botanists, unaware of the earlier publications, described many species again under new names.

With regard to the genus Coryphantha, the age development (ontogenesis) of many species renders classification difficult: a plant often spends several years in a juvenile state where its physical form is markedly different from that at a mature age, but the plant will often start flowering while still juvenile. This phenomenon has often led botanists to make their first descriptions based on young plants, thinking that they are new species.

Another factor leading to taxonomic problems is the high level of evolutionary development of the Coryphanthae sensu stricto, the Coryphantha stage (BUXBAUM 1956). Highly developed plants often become very similar even if they belong to very different branches of the evolutionary tree. This problem relates mainly to the flowers, which may reach such a high degree of simplification that no signifi cant differences can be observed. This factor makes a clear differentiation more difficult, considering the great variability.

In spite of all the confusion, today's nomenclature depends on the correct interpretation of the taxonomic history.

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