1954 年 3 巻 4 号 p. 250-270
The disjunctive distribution is the important and interesting problem of phytogeography. The flowering plants here treated represent 120 species belonging to 35 families. From the view point of the distribution-area, they are divided into ten groups, the number and percentage of the species of each group being as follows : [table] The south-western part of Hokkiado occupies the leading place for the Japanese and the Japanese-Chinese elements distributied in the temperate region. The coastal district of Prov. Hidaka also plays rather an important role for these elements. In the central part of Hokkaido, the mountains extending from north-north-west to south-south-east form the back bone of Hokkaido. The alpine plants of the Japanese element occur from south of the middle part ; they are Arenaria Katoana, Draba japonica, Alchemilla japonica Pedicularis apodochila and Anaphalis alpicola. They all occur in the mountains of various pretertiary rocks. It is very interesting that the peaks of the Daisetsu mountain group present good examples of the disjunctive distribution of the wide ranging arctic-alpine plants. As the Northern Pacific element are there Gentiana glauca, Taraxacum Chamissonis, Deschampsia pacifica and Juncus triglumis ; as the Pacific elements Minuartia macrocarpa, Gentiana algida and Artemisia trifurcata ; and as the Circumpolar elements Stellaria borealis, Pedicularis Oederi, Pedicularis verticillata, Sparganium hyperboreum, Phleum alpinum, Carex bipartita, Carex livida, Juncus castaneus and Juncus triglumis. The eastern part of Hokkaido is remarkable for the Eastern Asiatic and the Eurasiatic elements. As the Eastern Asiatic elements there are Chosenia bracteosa, Betula davurica and Rhododendron parvifolium, Urtica angustifolia ; and as the Eurasiatic elements there are Artemisia laciniata, Chrysanthemum vulgare, Sagittaria natans, Carex cyperoides, Herminium Monorchis and Gymnadenia conopsea.