XVI International Botanical Congess

Within the Asteridae, the monophyly of Ericales s. l. is strongly supported by rbcL data. The order comprises 24 families, usually not considered closely related, e.g. Ericaceae, Primulaceae, Polemoniaceae, and Balsaminaceae. The morphological and embryological variation is considerable and the morphological characteristics are few, but all members have tenuinucellate ovules, which is prevailing in the subclass, and many groups have endosperm haustoria. Basal relationships in the Ericales are unresolved, but there is strong support for groups such as Lecythidaceae-Scytopetalaceae, Sarraceniaceae-Roridulaceae, and Marcgraviaceae-Tetrameristaceae-Pellicieraceae-Balsaminaceae. Most families in the order are monophyletic, except Styracaceae, Theaceae, Primulaceae, and Myrsinaceae and it is anticipated that modifications in family circumscriptions will be necessary.