Vestured pits: their occurrence and systematic importance in eudicots

The distribution of vestured pits in secondary xylem reveals interesting patterns that may bear on hypotheses of phylogenetic relationships within eudicots. Vestured pits are found to be relatively widespread at the base of the eurosids I, eurosids II, and euasterids I, but the feature probably has been lost or originated independently in several more derived branches of these clades. Vestured pits characterise orders Myrtales and Gentianales sensu APG; other large monophyletic taxa that consistently show vestured pits include Malpighiaceae, Polygonaceae, Brassicaceae, and most Fabaceae. Representatives from euasterids Il always show nonvestured pits. The occurrence of the character implies numerous parallel origins in the following divergent, major taxa: (1) Proteaceae, (2) Polygonaceae (Caryophyllales). (3) eurosids I(Zygophyllaceae, Fabales, very few Rosales, Malpighiales), (4) eurosids II (Myrtales, Malvalus, Brassicales), and (5) euasterids I(Gentianales. Lamialus, Solanales). It is demonstrated that vestured pits frequently support results from DNA data.