Taxonomic Revision of Geranium sect. Dissecta (Geraniaceae)

Geranium section Dissecta (Geraniaceae) consists of four species centered in Eurasia, between the Mediterranean region and the Himalaya Mountains. In contrast to the current literature, we consider G. chelikii, and G. davisianum to be synonyms of G. sintenisii, and G. pallens to be a synonym of G. asphodeloides. We also accept G. dissectum and G. crenophilum, the latter sometimes considered as subspecies of G. asphodeloides. A multivariate morphometric study showed that some quantitative characters such as deeply divided leaves, shorter and narrower petals, and shorter filaments clearly distinguished the annual G. dissectum. The characters contributing most to separation of the three remaining perennial species were petal width and the length of glandular hairs of stem and pedicels. In G. asphodeloides and G. dissectum the rootstock and stem base has a very starch-rich parenchyma in the cortex, while in G. sintenisii and G. crenophilum the starch-rich parenchyma is mainly developed in the pith. A new key is provided, as well as new and detailed descriptions. Geranium crenophilum and G. sintenisii are here illustrated for the first time. Nine lectotypes and a neotype are designated, and distribution maps are presented. Analyses of the plastid trnL-trnF spacer, nuclear ITS sequences, and morphological data reveal that sect. Dissecta is strongly supported as monophyletic. In these analyses G. dissectum appeared as sister group to the rest of the species.