The natural history of the genus <i>Cypripedium</i> (Orchidaceae)

The genus <i>Cypripedium</i> is one of five monophyletic genera within slipper orchids. Nuclear ribosomal ITS, nuclear low copy gene (<i>ACO</i>) and plastid data were used for molecular clock analyses. According to these analyses, the most recent common ancestor of <i>Cypripedium</i> appeared in the early Eocene. The <i>Irapeana</i> section is the oldest phylogenetic line within <i>Cypripedium</i>. The analyses indicate that after the Middle Eocene Climatic Optimum (c. 41 Ma) three main evolutionary lineages were split. Other important evolutionary processes took place in the late Oligocene-early Miocene. In this period, there were numerous divergence events within species groups characterized by transcontinental disjunction.