Variation in the Eucalyptus globulus complex revisited

Patterns of variation in the <i>Eucalyptus globulus</i> Labill. complex are reassessed by combining capsule measurements from an earlier study with recent collections, mainly of subspecies <i>globulus</i>. Four groups of populations are apparent and can be ascribed to the four subspecies <i>maidenii</i>, <i>pseudoglobulus</i>, <i>bicostata</i> and <i>globulus</i>. Intergrade populations between the latter three subspecies are widespread and mainly occur in the Otway Ranges and west Gippsland. There is a continuum in capsule morphology between the three-fruited subspecies, <i>pseudoglobulus</i> and <i>bicostata</i>. Subspecies <i>globulus</i> intergrades with these three-fruited intermediates. Three-fruited intergrade populations occurring north and south of the range of core <i>pseudoglobulus</i> can be differentiated and probably represent intergrades between <i>pseudoglobulus</i> and <i>bicostata</i> and between <i>pseudoglobulus</i> and <i>globulus</i> respectively. Reports of <i>bicostata</i> in the Furneaux Group and southern Victoria are thus probably erroneous and result from convergence in capsule morphology. The previously described taxon <i>E. stjohnii</i> (R. T. Bak.) R. T. Bak. is part of the continuum between subspecies <i>pseudoglobulus</i> and <i>bicostata</i>, but closer to <i>pseudoglobulus</i>. Populations phenotypically intermediate between and significantly different from <i>globulus</i> and the three-fruited intergrades are highly variable and occur in western Tasmania, on the northern end of Flinders Island, in the Otway Ranges and in west Gippsland. An isolated population on Rodondo Island is highly variable and has closest affinities to <i>pseudoglobulus</i> despite being within the geographical range of core <i>globulus</i>. The population from King Island is intermediate between the Otway phenotype and core <i>globulus</i>. The climatic regimes of the subspecies are markedly different and most three-fruited and <i>globulus</i> intergrade populations have closer climatic affinities to <i>pseudoglobulus</i> and <i>globulus</i> respectively. Hypotheses relating to the origin of the pattern of variation in <i>E. globulus</i> are discussed.