| Abstract: | The pollen morphology and ultrastructure of exine of Podocarpaceae in Chinawere examined with light microscope, scanning electron microscope and transmission electronmicroscope. The pollen grains of Podocarpus have rather large and prominent sacs on bothsides of body, and are 53.9-74.8 μm long in total, with their bodies 29.6-45.2 μm long and19.1-31.3 μm wide. The sacs are smooth on outer surface with perforation, but reticulate inside. On distal view, they are obviously of radial muri from its base. The body is oblate orspheroidal, laddershaped on distal face. The exine of the capis tuberculate, but more distinctly on the margin than in the centre. The pollen grains of Dacrydium are of small and indistinct sacs around body, which are composed of many small bladders. The body is subcircularin outline. Both body and sacs are irrugulate tuberculate under SEM. Examination of thinsections of Podocarpus macrophyllus var. maki with TEM reveals that the exine includes ectexine and endexine. It is interesting to note that foot layer of ectexine possesses lamellar structure, but endexine is homogeneous in structure and lighter in colour. This character is specific in the gymnosperms. Based on informations of fossil pollen grains, Podocarpaceae is rather primitive and of ancient origin. |
