THE MORPHOLOGY OF POLLEN TETRADS AND VISCIN THREADS IN SOME TERTIARY,RHODODENDRON-LIKE ERICACEAE

The morphology of pollen tetrads and viscin threads is described in fo ssil Ericaceae pollen from various Eocene/Oligocene/Miocene localities in Europe (Germany, Austria), North America (eastern U.S.A.), and Asi a (eastern China). The typical characters of the tetrad configuration, the exine ornamentation and sculpturing, and especially the viscin th read morphology are extremely similar to or even indistinguishable fro m that in extant members of Rhododendron. All these pollen morphologic al features strongly suggest that all the investigated material can be assigned to a modern taxon of the Ericaceae: either to Rhododendroide ae or even to Rhododendron itself.