Oil glands and ducts in Eucalyptus L'Hérit. III. The flowers of series Corymbosae (Benth.) maiden

Abstract

Oil ducts are a constant feature of the flower in series Corymbosae. Their distribution in the tissues and their relationship to the vascular systems of the flower are described. Oil ducts occur in the pedicel and in the hypanthium and its extension as the tube of the flower. In all species ducts also underlie the nectary, a tissue the nature and distribution of which is defined and described. Ducts also occur in the ovary wall in all species.

In different species there are two distinctly different patterns of arrangement of ducts in the pedicels; two groups of species, A and B, can thus be distinguished. There are also three different patterns of arrangement of ducts in the hypanthium of the flower, corresponding to group A and two subdivisions of group B. It is further shown that the grouping of species based on the patterns of ducts in the pedicels and flowers conforms with that arrived at by consideration of other, unrelated characters, both floral and vegetative. The duct systems of the flower persist in the fruit and, as fruits or flowers are almost invariably available for examination, the pattern of arrangement of the ducts is of considerable use and importance to the taxonomy of the series Corymbosae.