311 Ericaceae in Malesia: vicariance biogeography, terrane tectonics and ecology Michael Heads Abstract Heads, Michael (Science Faculty, University of Goroka, PO Box 1078, Goroka, Papua New Guinea. Current address: Biology Department, University of the South Pacific, P.O. Box 1168, Suva, Fiji. Email:
[email protected]) 2003. Ericaceae in Malesia: vicariance biogeography, terrane tectonics and ecology. Telopea 10(1): 311–449. The Ericaceae are cosmopolitan but the main clades have well-marked centres of diversity and endemism in different parts of the world. Erica and its relatives, the heaths, are mainly in South Africa, while their sister group, Rhododendron and relatives, has centres of diversity in N Burma/SW China and New Guinea, giving an Indian Ocean affinity. The Vaccinioideae are largely Pacific-based, and epacrids are mainly in Australasia. The different centres, and trans-Indian, trans-Pacific and trans-Atlantic Ocean disjunctions all indicate origin by vicariance. The different main massings are reflected in the different distributions of the subfamilies within Malesia. With respect to plant architecture, in Rhododendron inflorescence bracts and leaves are very different. Erica and relatives with the ‘ericoid’ habit have similar leaves and bracts, and the individual plants may be homologous with inflorescences of Rhododendron. Furthermore, in the ericoids the ‘inflorescence-plant’ has also been largely sterilised, leaving shoots with mainly just bracts, and flowers restricted to distal parts of the shoot. The epacrids are also ‘inflorescence-plants’ with foliage comprised of ‘bracts’, but their sister group, the Vaccinioideae, have dimorphic foliage (leaves and bracts). In Malesian Ericaceae, the four large genera and the family as a whole have most species in the 1500–2000 m altitudinal belt, lower than is often thought and within the range of sweet potato cultivation.