Taxonomy of Cactaceae, Commelinaceae and formerly Coniferae, exploiting and encouraging the interface between professional botanists and knowledgeable amateur enthusiasts.

Basic taxonomy and nomenclature of various groups best understood from well-documented living collections, to provide support for scientific research into, e.g., chromosome evolution and molecular systematics, and for conservation and horticulture. Main focus since 1984 has been on Cactaceae and on international collaboration among professional researchers and amateur students of the family, culminating in the publication of the ‘New Cactus Lexicon' (2006), documenting and illustrating all taxa.