Morphology, anatomy and vasculature in leaves of Ginkgo biloba L. (Ginkgoaceae, Ginkgoales) under functional and evolutionary aspects

Abstract

Morphology and anatomy of leaves as well as germination in Ginkgo biloba were studied and compared to the situation in other gymnosperms. The results show that a long-shoot leaf will be replaced almost perfectly by the total leaf area of a single short-shoot, a feature which can be found in nearly all deciduous angiospermous, but is absent in all other deciduous gymnosperms. The results of the anatomical investigations of cotyledons and their comparison with the situation in other gymnosperm groups e.g. Araucariaceae, Pinacaea and Taxaceae demonstrate that the recent hypogeal germination of Ginkgo biloba might represent a feature derived from an epigeal ancestor with cotyledons taking part in photosynthesis and respiration. The cotyledons of Ginkgo biloba, however, have only a storage and haustorial function today, but they are still rich in chlorophyll and stomata are developed all over both leaf sides, despite the fact that they are never exposed to light.