Interaction of ecology, taxonomy and distribution in some Mesembryanthemaceae

Abstract

Many taxa of the family Mesembryanthemaceae show close correlations between distribution and
environmental factors, e.g. occurrence on limestone or quartzite only, but few cases have been studied in detail.
Recent investigations in anatomy, morphology, life cycles, physiology, and in energetic properties indicate that
fundamentally different patterns are developed in adaptation to arid conditions, even in reaction to identical
edaphic and climatic factors.
On the other hand, little is known about the immediate influence of changes in the natural environment.
Studies in populations of the subgenus Cephalophyllum of the genus  Cephalophyllum N.E. Br. show strong
correlations between precipitation data and habit, which can superimpose genetic dispositions. In addition, growth
forms are well adapted to certain types of plant communities, so that superficially, a diffuse structural pattern
results.
Long term studies, in the field and in the greenhouse, of growth forms in relation to time, to precipitation, and
to associations, allow first suggestions for adaptive pathways in the evolution of the group, and the results form a
basis for taxonomic decisions in this highly confused taxon. Finally, the example offers aspects for the better
understanding of interaction between ecology and distribution data.