A Preliminary Analysis of Phylogenetic Relationships in Viburnum (Caprifoliaceae s.1.)

In order to establish a working hypothesis of phylogenetic relationships within Viburnum, 23 presumably monophyletic units were scored for 34 characters, the polarity of the states of these characters was assessed (in most cases) by out-group comparison, and the data were analyzed using the WAGNER '78 computer program. Character state transitions were traced on the resulting cladogram; this helped pinpoint characters about which there was uncertainty concerning independence, homology, scoring, and/or polarity. The data were re-evaluated and a second cladogram was generated, which again prompted a re-evaluation of the characters. This process was continued until four cladograms were obtained. In interpreting these cladograms atten- tion was focused on the clades that were best supported by apomorphies and hence remained stable. Resolving the cladistic relationships of the labile clades requires additional data. The most important conclusions of this analysis are that the New World sect. Lentago and the subsect. Punctata of the Old World sect. Megalotinus are sister groups, and sects. Odontotinus and Opulus form a clade within which Odontotinus is paraphyletic. Viburnum contains about 120 species of shrubs and trees. It is widespread in the northern hemisphere and extends into the southern hemisphere in the mountains of Malesia and of South America. The region of greatest diver- sity is in eastern Asia but eastern North Amer- ica and the mountains of Mexico and Central and South America are also areas of high species diversity. Only five species are native to Europe