The genus Conophytum, distributed in the winter-rainfall regions of South-Africa and southern Namibia, is with about 100 species an unusually large genus for an arid land flora (Cowling et al. 1999). Although Conophytum is clearly defined by both vegetative and reproductive morphology the genus is considered taxonomically complex (Hammer 1993, 2002).

Within the Aizoaceae - Ruschioideae the genus Conophytum is notable for its variety in floral morphology, floral phenology, and flower opening time, and this morphological variability is paralleled by a great diversity of pollinators (Vogel 1954, Haas 1976, Liede and Hammer 1990, Hammer 2002). Since most Conophytum species are obligately outcrossing (Hammer, 1993), attracting pollinators is of great ecological and evolutionary significance. Remarkabel is the high number of night-flowering species and about 25% of the species are described as nocturnal. How can we explain this? And is pollination biology a key for the understanding of Conophytum evolution? We will try to give some answers to this questions on the following pages.     

The genus Conophytum - a study system for radiation and evolution

The genus has been intensively investigated in the last years by hobbiists and scientists. Hobbiists are certainly attracted by their small size and the high variation of the beautiful bodies and flowers, but what makes them so attractive to scientist? 

(1) We find well documented information on populations - The number of populations described is until now about 2000. There are numerous descriptions and well documented colour pictures on many of these populations (see Hammer 1993, 2002). We suppose that on the population level, this genus is the best documented plant group. 

(2) The genus shows a relatively restricted distribution - Conophytums are found mainly in the winter-rainfall regions of South-Africa and southern Namibia. This makes investigations, encompassing the whole genus,  much easier.

(3) There exists a recent revision - There is an excellent revision (Hammer 1993) of the genus based on morphological data. Moreover, in his second book "Dumpling and his wife – new views on the genus Conophytum" (Hammer 2002) Steven Hammer brings a lot of new data on the taxonomy, morphology, and other interesting fields.

(4) We find a high floral variation within the genus Conophytum - The high variety in floral morphology, floral phenology, and flower opening time in genus is paralleled by a great diversity of pollinators. This allows to study the interaction of Conophytum species with different pollinators. Of particular interest are the differences between day- and night-flowering species. Adaptation to different pollinator guilds might have been an important factor for the reproductive isolation of species.

Literature:

Cowling R.M., Esler, K.J. & Rundel, P.W. 1999. Namaqualand, South Africa - an overview of a unique winter-rainfall desert ecosystem. Plant Ecology 142: 3-21.

Hammer, S. 1993. The Genus Conophytum - A Conograph. Succulent Plant Publications, Pretoria.

Hammer, S. 2002. Dumpling and His Wife: New Views of the Genus Conophytum. East Anglia Engraving Creative Colour Ltd, Norwich, England.

Haas, R. 1976. Morphologische, anatomische und entwicklungsgeschichtliche Untersuchungen an Blüten und Früchten hochsukkulenter Mesembryanthemaceen-Gattungen. Ein Beitrag zur Systematik. Dissertationes Botanicae 33. Vaduz, Cramer.

Liede, S. & Hammer, S. 1990. Aspects of floral structure and phenology in the genus Conophytum (Mesembryanthemaceae). Plant Systematics and Evolution 172: 229- 240.

Vogel, S. 1954. Blütenbiologische Typen als Elemente der Sippengliederung. Botanische Studien Heft 1. Fischer, Jena.

_{Andreas Jürgens}