On the Occurrence of Amphistomatic Leaves in Ginkgo biloba L.

In 1957 Maacz reported the occurrence of cell configurations in the upper epidermis of the leaf of Ginkgo biloba L. suggesting the presence of rudimentary stomata. Maacz speaks, very cautiously, of “rudimentaren Spuren der Spaltoffnungen”, i.e. rudimentary traces of stomata. This observation is of interest because of the fact that Ginkgo biloba is regarded as a. typically hypostomatic species. An investigation of material obtained from four different specimens of this tree growing in the Leyden Botanical Garden revealed that the upper side of leaves from long shoots from a male tree and from a juvenile tree of still unknown sex exhibited normal stomata. The brachyblast leaves of the same trees, however, are distinctly hypostomatic. Examination of leaves from both long shoots and brachyblasts of our two female specimens showed both types of leaves to be hypostomatic. Furthermore, the leaves from a water shoot sprouting directly from the trunk of the male tree were also found, contrary to expectation, to be hypostomatic. A possible correlation between the occurrence of stomata in the upper leaf epidermis and a more primitive type of leaf shape is discussed. This point is interesting because of the fact that fossil leaves of Ginkgoaceae from earlier geological periods are amphistomatic.