Abstract: In order to construct phylogenetic relationships of the family Smilacaceae, 79 species representing all genera and sections of the family from all over the world were used for cladistic analysis, with Philesia and Lapageria of Philasiaceae as outgroups. A matrix of 36 binary and 11 multistate morphological characters was constructed. The first parsimonious analysis yielded numerous most parsimonious trees of 275 steps, and then 82 most parsimonious trees with 40.729 steps length were produced by reweighting characters using maximum values of rescaled consistency (RC), which remained stable after the second reweighting. There is a moderate resolution but generally poor bootstrap support for the phylogenetic relationships in the family. From the strict MP tree and the NJ tree, Ripogonum is a sister to Smilax, but may be better treated as a separate family. Heterosmilax is considered to be derived from ancestral Smilax and occurs as the most derived clade of the Smilacaceae, and thus it is reasonable to retain it as a section in Smilax s.l. Within Smilax most currently recognized sections are polyphyletic, but some major lineages are distinct. The herbaceous Smilax species form a monophyletic clade, and it is also the case for the South American species. Their positions in the cladogram are intriguing and may help to shed light on evolutionary and biogeographic history of the family.

Key words: Smilacaceae, Smilax, Heterosmilax, Ripogonum, morphology, cladistics, phylogeny.