XVI International Botanical Congess

The Asteridae s.l. includes almost all sympetalous dicotyledonous plants. A correlation between sympetaly and unitegmic-tenuinucellate ovules has been noted by Warming in 1878 and later correlations with cellular endosperm and iridoid compounds have been noted by Dahlgren. Phylogenetic analyses using sequences of multiple genes have improved our understanding of the evolutionary history of this large clade. I use the resulting phylogenetic tree to elucidate the evolutionary patterns of the ovule and the diversification of iridoid biosynthesis in Asteridae s.l. Unitegmic-tenuinucellate ovules occur almost universally in the Asteridae s.l. Nuclear endosperm emerged several times independently and reversals do not occur. Iridoids occur in many asterid clades and are probably ancestral in the Asteridae s.l.