CONTRASTS IN CROWN DEVELOPMENT OF THE MISTLETOES ALEPIS-FLAVIDA (HOOKF) TIEGH AND PERAXILLA-TETRAPETALA (L F) TIEGH (LORANTHACEAE) PARASITIC ON NOTHOFAGUS-SOLANDRI (HOOK F) OERST, CRAIGIEBURN ECOLOGICAL DISTRICT, NEW-ZEALAND

The developmental features of Alepis flavida and Paraxilla tetrapetala , two parasitic Loranthaceae mistletoes endemic to New Zealand, are de scribed for a better understanding of their comparative ecologies. The two species were found to have strikingly different modes of developm ent. Alepis flavida develops monopodially from preformed buds, with li ttle branching, while Peraxilla tetrapetala develops sympodially, and frequently bifurcates, after shoot-tip abortion from submerged buds wi th little performed content, and with much branching. These two patter ns produce distinctly different clump froms: loose clumps, with long l imbs and few orders of branches, in Alepis flavida, and densely branch ed clumps, with many orders of branching, in Peraxilla tetrapetala. Bo th species produce runners, but in Peraxilla tetrapetala these spread to adjacent locations (often the trunk) and produce extremely large, m ultiple clumps, whereas Alepis flavida remains on the branch on which it established. This difference in development allows these two specie s to exploit similar niches in Nothofagus solandri forests. The develo pmental differences observed here support the taxonomic segregation of Alepis and Peraxilla.