Janine E. Victor

The Red List of South Africa is a useful tool for assessing conservation priorities, and furthermore, provides insight into areas where information is lacking and future research thrusts are needed. Succulents are prone to threats from overharvesting, and also have an unusually high number of species classified as Data Deficient due to lack of information. Our analyses show that in South Africa, the Asphodelaceae are the most threatened of the succulent plant families and are therefore most in need of conservation attention. Mesembryanthemaceae have the highest proportion of (and highest number of) Data Deficient species and are therefore most in need of future research efforts. It is concluded that succulents are particularly vulnerable to threats because of their relatively slow growth compared with other herbaceous plants, coupled with their desirability in the horticultural industry. Die Rote Liste von Südafrika ist ein nützliches Werkzeug, um Natursch-utzprioritäten zu beurteilen. Darüberhinaus bietet sie aber auch Einsichten, in welchen Gebieten Kenntnisse fehlen und wo zukünftige Forschungs-schwerpunkte nötig sind. Sukkulen-ten sind besonders durch übermässiges Sammeln gefährdet, und überdurchschnittlich viele Arten sind wegen fehlenden Angaben als “data deficient” aufgelistet. Unsere Analysen zeigen, dass in Südafrika unter allen Sukkulen-tenfamilien die Asphodelaceae besonders gefährdet sind, und dass hier deshalb besondere Aufmerksamkeit nötig ist. Die Mesembryan-themaceae haben im Verhältnis wie auch absolut die höchste Zahl Arten mit dem Status “data deficient”, und deshalb braucht es hier besondere zukünftige Forschungsanstrengungen. Zusamm-enfassend wird deutlich, dass Sukkulenten wegen ihres im Vergleich zu anderen krautigen Pflanzen langsamen Wachstums, sowie bedingt durch ihren grossen Stellenwert in der Garten-bauindustrie, besonders verletzlich sind.

The pollen morphology of Diosma and Coleonema of the taxonomically problematic subtribe Diosminae (Rutaceae) was investigated to determine its taxonomic relevance. Pollen of 26 of the 28 species of Diosma and of each of the eight species of Coleonema was investigated by LM, SEM and TEM. In pollen of Diosma the exine sculpturing is uniform, and only one pollen type, reticulate, could be distinguished. In contrast, exine sculpturing shows interspecific variation in Coleonema and three distinct types, striate, reticulate and perforate, could be discerned. Species groupings indicated by the pollen types suggest possible relationships between species within Coleonema and with other genera that were not previously apparent. Pollen data support macromorphological evidence that suggests the generic re-classification of the Diosminae.

The pollen morphology of Adenandra Willd. (Rutaceae: Diosminae) was investigated to determine its taxonomic significance. Pollen of 27 of the 30 infrageneric taxa (representing 16 of the 18 species) was investigated by LM, SEM and TEM. Adenandra differs from all other Diosminae in having 4-colporate rather than 3-colporate pollen grains. This supports the alleged monophyletic status of the genus. Exine morphology and structure, however, is extremely diverse considering the size of the genus, with eight distinct pollen types and four subtypes being discerned. In some members the grains have uniform macroreticulate, striate or striato-reticulate sculpturing, whereas in others the poles have striate, striato-reticulate or reticulate-perforate sculpturing with various types of reticulate or rugulate sculpturing at the mesocolpia. Taxonomic groupings revealed by the pollen characters suggest elationships between taxa that were not previously apparent. It is suggested that evolutionary diversification among species of Adenandra is often more strikingly reflected by pollen morphology than by macromorphology, hence the eurypalynous state of the genus.