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Composition, Origin, and Affinities of the Madagascan Vascular Flora

1978; Missouri Botanical Garden; Volume: 65; Issue: 2 Linguagem: Inglês

10.2307/2398861

2162-4372

Jean‐F. Leroy,

Plant Taxonomy and Phylogenetics

e Madagascan vascular flora which is composed of over 160 families is exceptionally interesting not only because it is prodigiously rich and diversified, but because it has preserved a number of relicts.In this review, presented roughly according to the "E nete system of Cronquist, every family has been tentatively, although shortly, analyzed wih regard to its composition, origin, and affinity.The hypothesis that the Madagascan flora was a part of the large Cretaceous Gondwanian flora at the time when Angiosperms originated and that the flora became greatly impoverished on the African continent due to far-reaching climatic changes accounts for many present characteristics of the Madagascan flora.In this context the existence of a Madagascan region sensu lato (Madagascar, Mascarene Islands, tae and southern Africa), where many austral genera or taxa of higher taxonomic rank exist-some of which belong to Magnoliidae and to the most primitive parts of Dilleniidae and Rosidae-becomes understandable.Equally understandable become SE discontinuities of range and the existence of many endemic uni-or paucispecific genera.Briefly, the present Madagascan vascular flora probably resulted from a progressive dere on "of the bonds cu led stock and natural Em of taxa in time through lone cist bo.dodi In this paper, I do not intend, of course, to present an exhaustive enquiry concerning the origins and affinities of the Madagascan flora.I think an enormous amount of basic research remains to be done in order to get an accurate general view on the matter.And how could we do so, since we mostly cannot establish a satisfactory connection between taxonomic classification and distributional patterns, in order to express the true taxogenesis?Since Perrier de la Bathie and Humbert's geographical works on the Madagascan flora many papers and books have been published, but no new concept significant enough to have important implications has been proposed.Some recent publications of great interest pertaining to this matter have appeared, but they are not especially devoted to Madagascar.A very limited number of valuable papers have to be mentioned, insofar as they contribute to Madagascan phytogeography, such as those by Stearn (1971), Dejardin et al. (1973), Koechlin et al. (1974), Wild (1975).In fact, any attempt at a comprehensive synthesis of this kind at this time would be premature because we need to know much more with respect to palaeobotany and phylogeny.Although no important general conclusion has been reached concerning the biogeography of the Madagascan plants for some decades, the same does not hold true for strictly taxonomic knowledge, which has much progressed, thanks in particular to outstanding research by the late forester and botanist R. Capuron.We are indebted to him for an exceptional improvement in the analysis of the woody plants of Madagascar.But even in taxonomy we are far from having