Chloroplast (trnL-F and rbcL) sequences were used to reconstruct the phylogeny of Geraniaceae and Hypseocharitaceae. According to these data Hypseocharitaceae and Geraniaceae are monophyletic. Pelargonium and Monsonia are sisters to the largest clade of Geraniaceae, formed by Geranium, Erodium and California. According to molecular dating and dispersal-vicariance analysis, the split of the stem branches of Geraniaceae probably occurred during the Oligocene, in southern Africa or in southern Africa plus the Mediterranean area. However, their diversification occurred during the Miocene, coinciding with the beginning of major aridification events in their distribution areas. An ancestor of the largest clade of Geraniaceae (Geranium, Erodium, and California) colonised a number of habitats in the northern hemisphere and in South American mountain ranges. In summary, the evolution of the Geraniaceae is marked by the dispersal of ancestors from Southern Africa to cold, temperate and often disturbed habitats in the rest of world, where only generalist pollination and facultative autogamy could ensure sufficient seed production and survival.

Aim This paper reports the diversity and endemism patterns of African ferns, and explores the potential role of diversity refuges and environmental and historical factors in the shaping of these patterns. Material and locationsThe extant fern taxa occupying Africa south of the Sahara, Madagascar and some islands of the South Atlantic.Methods The number of taxa in each area or operational geographical unit (OGU) was scored, and the correlation between this number and physical and climatic variables analysed by standard pairwise and stepwise multiple regression analysis (SPR and SMR). The effects of biological factors such as dispersal capacity, reproductive biology, genetic features and certain physiological adaptations were evaluated by comparing the number of species in each OGU. Floral affinities among OGUs were analysed using non-metric multi-dimensional scaling (NMS) and parsimonic analysis of dispersion (PAD), and compared with b-turnover and inter-OGU distances.Results OGU area, elevation and the distance between refuges determined the composition of local floras, but only greater OGU area and the existence of higher maximum elevations increased species richness. The distance between refuges also affected the number of endemic species, especially on islands. The biological features studied only slightly influenced fern distribution. The main climatic predictor of species number was humidity. SPR and SMR revealed three main groups of ferns with different ecological trends. NMS and PAD analyses separated the four areas of highest diversity in Africa, three of which are inhabited by ferns with distinct ecological requirements. The fourth area was Madagascar, which shows an accumulation of endemic and relict diversity that is not easy to explain. Main conclusionsThe distribution of ferns in Africa has been influenced by refuges. These probably allowed many species to recolonize the neighbouring areas after the extinctions of the Pleistocene. Three major components were detected in the African flora: Guinea-Congolian thermophilous, cold-tolerant Afro-montane, and Southern drought-tolerant elements. These are related to the three main refuge areas, i.e. the Gulf of Guinea area, the eastern tropical region, and the Cape region. Endemicity in ferns was found to be lower than that of seed plants due to the higher dispersability of fern spores. The distance between OGUs seems to be the main predictor of the number of endemic fern species these areas contain.

Taxonomic revision of Geranium sect. Gracilia (Geraniaceae). Brittonia 55: 93-126. 2003.-Geranium sect. Gracilia (Geraniaceae) comprises nine species in the Andes of Venezuela and Colombia. Geranium lindenianum and G. gracilipes are synonymized with G. holosericeum. The identity of G. multiceps is clarified. Its differences from the two Colombian species, G. santanderiense and G. lainzii, are discussed. Geranium lignosum, G. sebosum, G. stoloniferum, G. subnudicaule, and G. velutinum are now considered to be members of sect. Gracilia. The identity of G. pUgerianum could not be clarified because the type was destroyed and other collections have not been found. Micromorphological leaf and seed characters are discussed. Six lectotypes and one neotype are designated.