[Evolution of succulent Senecioneae (Asteraceae) of Southern Africa].

Southern African succulents of tribe Senecioneae are likely to have come from non-succulent inhabitants neighbour mesic to semi-arid areas of S to SE Africa. Four phyla are believed to have evolved successively in situ by colonizing arid regions of SW Africa. The Senecio medley-woodii-phylum must have been the first one to have developed the succulent syndrome. Its members are densely pubescent leaf-succulent herbs without special water-storage tissue in their leaves. This phylum seems to have been followed by Othonna-phylum which has mostly developed caudex/bulbous growth habit with annual hemi-succulent to non-succulent shoots. Some Othonna species are stem succulents and a few ones are leaf-succulents. No one species has dense indumentum, however. Curio species and some succulent Senecio ones constitute the unit alias Curio-phylum. Interrelationships between these species remain still unresolved. The Curio-phylum might have evolved a little bit later than the Othonna-phylum. Contrary to the latter, only 2 representatives of the Curio-phylum are bulbous herbs with annual hemi-succulent shoots and only 1 species is a stem succulent. The 3 species mentioned all occupy territories outside areas of Othonna species of similar growth habits. None of them has indumentum. Most members of the Curio-phylum are glabrate leaf succulents with special water-storage tissue in their leaves. We believe that specific succulent syndrome of each phylum indicates specific adaptive zone it occupies in arid regions of SW Africa (though we are unable to characterize these zones distinctively). These differences in succulent syndromes must enable the 3 phyla to coexist in numerous arid areas of SW Africa. Moreover, the differences evidently enable them to "close" competitively these areas to the latest Kleinia-phylum. Then, the species of the Kleinia-phylum inhabit semi-arid areas of SE Africa and semi-arid to arid areas of E & N Africa, Canary Islands and Arabia. Only a few stem succulent Kleinia species live in those arid areas of the SW Africa where there are neither stem succulent othonnas nor stem succulent curios. Evolution of the succulence in Southern African Senecioneae thus outlined fits the Gause's competitive exclusion principle.

[Morphological and molecular data on the origin of angiosperms: on a way to a synthesis].

Molecular phylogenetic data have drastically changed the views on the phylogeny of higher plants. All the extant gymnosperms were asserted as a monophyletic group opposed to the highly isolated angiosperms. The 'Anthophyte Theory' was thus rejected. The identification and analysis of gymnosperm orthologues of genes regulating flower development in angiosperms resulted in the formulation of the 'Mostly Male Theory' of the evolutionary origin of flower; this theory does not contradict the concept of monophyly of all the extant gymnosperms. The Mostly Male Theory assumes that the origin of angiosperms was caused by a loss of the Needle family gene that effected ovuliferous (female) organs and the translocation of the ovules onto the adaxial side of some of the (male) leafy microsporangiophores. Having acquired ovules, the former microsporangiophores started evolving into the carpels. The prerequisite bisexual design of the ancestral fructification thus becomes unnecessary. Indeed, this assumption suggests the deriving of Angiosperms from any gymnosperm plant with leafy microsporangiophores. The problem of carpel origin has subsequently changed to some degree into the problem of the origin of the bitegmic anatropous ovule presumably inherent in ancestral Angiosperms. The Mostly Male Theory consideredeither Corystospermataceae (= Umkomasiaceae) or Caytoniaceae to be the forerunners of such an ovule. Yet the capsules of Corystospermataceae distinctly differ from angiosperm ovules in the locations of their adaxial/abaxial sides, while Caytoniaceae had no leafy microsporangiophores. This inconsistency suggests that functions of the Needle family regulatory genes in Gymnosperms should be much better understood to appraise properly both the possibilities and the consequences of their hypothetical loss by the emerging angiosperms. Moreover, the extant gymnosperm groups are actually held as monophyletic and contrasted to Angiosperms on the basis of analysing the unrepresentative scant remnants of these, mostly extinct, taxa. Therefore, traditional botanical and paleobotanical data should not be rejected. In any case, Meyen's idea angiosperms origin from Bennettitales is worth being retained as a hypothesis to be tested with new results of both paleobotany and molecular biology.