The distribution of Eucaiyptus cypellocarpa, E. goniocalyx and four populations apparently morphologically intermediate between these two but isolated from them is described in an area near Melbourne, Victoria. Scatter diagrams of various characters from both mature trees and progeny document and confirm that the four populations are intermediate. However, the variability of their progeny is not markedly different from that of the‘pure’ species and is not as high as that of recent hybrids between the two species. It is suggested that the four populations represent either old hybrid swarms now stabilized by selection from which the parents have disappeared, or that they arose without hybridization (a) by selection from a single species or (b) as a former cline between both species. The difficulties in interpreting the origins of such stands are pointed out.