The classification and distribution of the genus Picea is reviewed in this paper. A few of the 34 species recognized are widely distributed in the boreal zone of the Northern Hemisphere, while almost all of the others are relics and are distributed in restricted areas. Twenty species, more than the half of the whole genus, are endemic to the Sino-Japanese region. According to palaeobotanical data, the more primitive group, sect. Omorika and sect. Sitcha as defined by SCHMIDT, occurred through the early Tertiary. The advanced groups, sect. Picea and sect. Pungentes, differentiated in the late Tertiary. After the ice age of the Quaternary, some new members of sect. Picea extented their areas to the boreal zone. Following a taxonomic key to the species and varieties, all the taxa of the Japanese Picea including forms are annotated together with distribution areas. The cone scales of each species are shown by illustrations (Fig. 3).
In this paper we categorized the ages of macroscopic and microscopic rice remains, e. g., fruit, stems, pollen grains and plant opal; stone and wood artifacts used for rice cultivation; and paddy fields and other facilities related to production. Then the history of rice cultivation and the relationship of culture and rice, from the Latest Jomon to the Early Yayoi periods in Japan. Significantly plant opal analysis of pottery composition was found to be an effective method for dating the rice cultivation in prehistory.
Wood peat found at some excavations in the alluvial plains of central Japan were deposited mostly during the Middle Jomon to the Latest Jamon Ages, 4,500~2,500 y. B. P. They are characterized by a high water content, a low degree of stratification, a heterogeneous composition of wood or wood fragments, and a low mineral content. The wood peat consists of macroscopic remains such as roots, stumps, trunks, branches, seeds and fruits of trees, and contain many pollen grains of their dominant or abundant taxa. Palaeobotanical studies of wood peat revealed that the vegetation consisted of fen wood or fen carr communities such as Alnus- Fraxinus forest with some herbaceous plants, and were formed under the mesotrophic to eutrophic nutrient status at or above the water table.