Studies in the Comparative Anatomy of the Ericales I. Ericaceae-Subfamily Rhododendroideae

Abstract

The wood anatomy of 53 spp. in 19 genera of the Rhodo-dendroideae is described, and a comparative study of the diagnostic anatomical characteristics is made. These data, incorporated with traditional taxonomic criteria of floral structure, growth habit, etc., become the basis of a new phylogenetic system of classification of the Rhododendroideae. Five tribes are recognized, 4 of which have been established previously. The Cladothamneae, Phyllodoceae and Rhodo-dendreae, along with the proposed DABOECIEAE, are demonstrated to have arisen from a common ancestor. The Bejarieae appear to be of different ancestry. Little interchange of genera between the established tribes has been necessary but much new light is cast on the phylogenetic relationship of genera within the tribes.