The tapetum in basal angiosperms: Early diversity

The distribution of tapetal types in basal angiosperms is reviewed both fro m the literature and new observations in the context of recent phylogenetic analyses. Secretory tapeta predominate among land plants. The majority of basal angiosperms share a secretory tapetum with their anthophyte ancestors . Plasmodial and invasive tapeta are relatively rare in eudicots but have e volved several times among early-branching angiosperms, especially in monoc otyledons, in which they have evolved three or more times. The invasive tap etum has evolved at least four other times independently in basal angiosper ms: in Nymphaeaceae, Annonaceae, Monimiaceae, and Winteraceae. Plasmodial t apeta are mostly found in monocotyledons but have evolved at least twice in basal angiosperms, in Annonaceae, and in Hernandiaceae/Lauraceae. This app arent plasticity for a relatively brief but critical time in angiosperm evo lution may reflect the early evolution of highly specific pollination syndr omes.