The Ericales project aims at a better understanding of the phylogenetic interrelationships in the order Ericales.
Investigations based of molecular data have shown that this order comprise the families Marcgraviaceae, Tetrameristaceae, Pellicieraceae, Polemoniaceae, Fouquieriaceae, Theaceae, Ternstroemiaceae, Sladeniaceae, Pentaphylacaceae, Symplocaceae, Styracaceae, Diapensiaceae, Lecythidaceae (incl. Scytopetalaceae), Sapotaceae, Ebenaceae (incl. Lissocarpaceae), Maesaceae, Theophrastaceae, Primulaceae, Myrsinaceae, Actinidiaceae, Roridulaceae, Sarraceniaceae, Clethraceae, Cyrillaceae, and Ericaceae.
The Heath family, Ericaceae, has in a number of publications been demonstrated to be a paraphyletic assemblage of genera. Preliminary cladistic analyses of morphological as well as molecular data indicate that the families Pyrolaceae, Monotropaceae, Empetraceae and Epacridaceae, all have evolved from ancestors within the Ericaceae. The East Asian genus Enkianthus with less than 20 species, is the sister group of all other Ericaceae. The species of the 'Pyrolaceae' and the 'Monotropaceae' constitute a small monophyletic group forming specialized mycorrhizal associations. The 'Empetraceae' belong to the subfamily Rhododendroideae and are adapted to wind pollination, as indicated by their reduced flowers with enlarged and lobed stigmas. The mainly Australian group 'Epacridaceae' are related to the Andromedoid-Vaccinioid complex, but have a reduced number of stamens.
Ericaceae is sister to Cyrillaceae, and together they are sister to Clethraceae. To the same clade belongs also Actinidiaceae, Roridulaceae, and Sarraceniaceae.
The Ericales research project is supported financially by the Swedish Natural Science Research Council (VR), and different parts are conducted in cooperation with Kathleen A. Kron (Winston-Salem), Scott Mori (New York) and Chih-Hua Tsou (Taipei), Mari Källersjö, Ulf Swenson and Per Ola Karis (Stockholm), and include Ph.D.-student Ulrika Manns.