CATAPHYLLS AND TAXONOMY IN PHORADENDRON AND DENDROPHTHORA (VISCACEAE)

The occurrence of basal cataphylls is surveyed in Phoradendron and Den drophthora (Viscaceae). It is shown that, in the former genus, there i s a great deal of irregularity in this regard, rendering the maintenan ce of Trelease's distinction between his Boreales and Aequatoriales ex tremely difficult, and at times misleading or even impossible. In both Trelease's groups, a number of cataphyll irregularities are detailed. Some of these appear to represent the development of basal cataphylls from acataphyllous stock, but in other cases it seems that acataphyll ous species have evolved from ancestors bearing such organs. In each g enus, the lowest foliar organs of lateral stems are positioned in one of two phyllotactic patterns, transverse or median. The systematic imp ortance of this difference is almost exclusively at the species level. Tn both the occurrence of basal cataphylls and in basal phyllotaxy th e type species of Phoradendron, P. californicum, occupies an anomalous position in the genus; nomenclatural consequences are briefly indicat ed.