The Vitaceae, or grape family, contains around 900 species and 15 genera mainly having the liana growth form. Extant members of the family exhibit interesting geographical distribution patterns. Some genera are strictly regional; others display North America-Asia disjunction pattern. The family have a rich fossil record, particularly of seeds, in the Tertiary. Seeds of Vitaceae can be readily recognized by unique characters such as a dorsal chalaza and a pair of ventral infolds, and fossil seeds frequently have been identified to extant genera. The fossil seeds are potentially useful for inferring the past geographical distribution patterns of Vitaceae.

To test whether seeds of Vitaceae can be identified to the generic level and used to properly identify/assess fossil seeds, 252 seeds, representing all 15 extant genera including the closest relatives Leea, were sampled for morphometric analyses. Seeds of genera mostly can be distinguished by a set of characters, nevertheless, some genera have very similar seeds. Such similar seeds may indicate closer phylogenetic relationships among these genera. Besides similarity comparison, a phylogeny of the family is also needed to interpret fossil affinities.

Although intrafamilial relationships have been inferred previously from molecular work, none of these studies sampled all of the genera. Phylogenetic analyses based on morphological data have not been done previously. The morphological phylogeny presented here includes all genera of the family using 80 non-seed characters, plus 57 seed characters from the morphometric analyses. To test different theories of homology, the continuous characters are treated using two different coding methods. The morphological phylogeny resolves the 4-petaled genera as earlier branching lineages, sister to a clade containing primarily 5-petaled genera.

Most fossil seeds from the Tertiary are indistinguishable from the extant seeds externally, however, some show combinations of characters not present in the sampled modern seeds. The affinities of six selected better preserved fossils were additionally tested by morphometric analyses and cladistic methods. Fossil seeds with oval chalazas are much more abundant than the ones with linear chalazas or perichalazas. The distribution of the fossils suggests that the lineages bearing perichalazal seeds have been restricted to the tropical regions since the Eocene.