In this electron microscopic studies, the stratigraphical structure of the pollen walls of 35 families of Magnoliales and Amentiferae etc. was analysed from ultra thin sections of non acetolyzed pollen grains. The characters of the sporoderm are represented by the structure of the sexine : (Echinate, spinose) Nuphar, Euryale, Brasenia. (Spinulose) Nelumbo, Clematis, Liquidambar, Juglans, Carya, Myrica, Alnus, Betula, Ostrya, Urtica. (Psilate, without spine) Magnolia, Michelia. (Clavate intectate and baculate intectate) Cabomba, Acer, Chrysanthemum, Centaurea. (Punctitegillate, tectum perforate without spine) Liriodendron, Illicium, Meratia, Salix, Populus, Fagus, Quercus. (Granular) Carya, Ulmus, Rhododendron. By electron microscopy the presence of a micropore was confirmed. The pores are numerous and large in the pollen grains of group such as Fagus, Quercus and Populus, and in this group the sexine is rough and corrugate. (Micropore present) Cabomba, Brasenia, Nymphaea, Meratia, Polypara, Nelumbo, Clematis, Liriodendron, Illicium, Liquidambar, Salix, Populus, Fagus, Quercus, Shiia. (Micropore absent) Nuphar, Victoria, Ranunculus, Magnolia, Alnus, Ostrya, Corylus, Urtica, Juglans, Myrica. The presence of a comfit type perine (Spinose spheroids bodies after R_<OWLEY> 1959) was seen with an electron microscope : Ranales (Meratia), Amentiferae (Juglans). According to the structure of pollen walls, Ranales is recognized as one of the most variable forms of Dicotyledoneae. From the present results of stratigraphical studies on pollen walls, Ranales is related to Amentiferae. The relationship between members of Amentiferae (Juglandales, Myricales, Fagales and Salicales) judged from the structure of the pollen walls are in accord with prevailing taxonomical relationships. The interrelationship between plants in Dicotyledoneae together their phylogenetical and other palynological characters will be discussed in detail in another paper.

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1.Dermatocarpon miniatum is widely distributed in the world, and the occurrence of this saxicolous lichen is usually connected with streams. 2. Ecological observations of Dermatocarpon miniatum were carried out on the river Kagami in Tosayama, Kochi Prefecture. 3. The floristic composition of the community accompanied by Dermatocarpon miniatum is characteristic. Especially, such lichens as Thyrea kisegawaensis, Verrucaria sp., and Endocarpon sp. are noticeable. 4. As shown in Table 2 and Fig. 1, Dermatocarpon miniatum is mostly found on rocks frequently submerged in the water. The habitat of the community is similar to that of the Salix gracilistyla community.

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