Taxonomic revision, phylogenetics and transcontinental distribution of Anemone section Anemone (Ranunculaceae)

The monophyletic Anemone section Anemone (Ranunculaceae) includes predominantly diploid and outbreeding geophytic perennials. A revised taxonomy of the section with 16 species (and some infraspecific taxa) is proposed on the basis of a critical morphological analysis of living populations and extensive herbarium material, together with karyological, cytogenetical and DNA-analytical data. A key, descriptions, figures illustrating some type specimens and differential characters, examples of seedling development and pollen grain micromorphology (scanning electron microscopy) and distribution maps are presented. The position of A. section Anemone within the family is illustrated by a plastid DNA phylogram from sequences of the atpB-rbcL intergenic region. A penalized likelihood approach permitted the approximate dating of the origin and major differentiation phases of the section. The analysis of 20 morphological characters from all species of A. section Anemone with A. blanda (A. section Tuberosa) as an outgroup resulted in a morphology-based phylogram which supports the recognition of four subsections, i.e. Somalienses (one species, northern Somalia), Anemone (three species, Mediterranean area), Biflorae (five species, South-West and Central Asia) and Carolinianae (seven species, North and South America). These data allow a discussion of the phylogenetic diversification and stepwise expansion of the section since the late Miocene (c. 9 Mya). Partly by long distance dispersion, section Anemone has developed from a palaeo-Mediterranean ancestor to its present transcontinental distribution. (C) 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160, 312-354.