The Relationship of Some Populations Involving Eucalyptus Cypellocarpa and E. Globulus to the Problem of Phantom Hybrids

Summary A taxonomically anomalous population of eucalypts at Mallacoota, Victoria, is mapped and studied in detail. Measurements of adult and seedling morphology show the population to be intermediate between Eucalyptus globulus and E. cypellocarpa. However, on leaf terpenoid data the population is indistinguishable from E. cypellocarpa. The very restricted distribution of the population, and the high variability of its adult morphology suggest that it arose by hybridization between the two species named above. As the nearest stand of E. globulus is 6.4 km away, the population may represent a phantom hybrid stand. It is inferred from distribution data that E. globulus stands may have been present in the area before submergence by rising sea levels. If any pure E. globulus trees remained, a preponderance of E. cypellocarpa pollen may have prevented the continued production of more preponderant E. globulus progeny.