Introduction 



Marsh Plants and Others Common Along Streams 



Caltha palustris 

 Carex dickinsii 

 Carex dispalata 

 Cypertts glomerattis 

 Eleocharis spp. 

 Eriocatdon spp. 

 Lycopus uniflorus 

 Rhynchospora spp. 



ScirptiS juncoides 

 Scirptis lacustris var. creber 

 Scirpus mitsu^imanus 

 Scirptis preslii 

 Scirpus triqueter 

 Scirpus wichurae 

 Sparganittm stolonijerum 

 Typha latijolia 



The temperate flora of Japan shows close relationship to that 

 of certain areas of mainland eastern Asia, especially with the 

 mountainous areas of southern Korea and the lowlands of cen- 

 tral Korea and the Huan River valley, also with the mountain- 

 ous regions of central China and the high mountains of the 

 Himalaya and Malaysia. 



Genera Common to the Temperate Floras of Japan 

 and the Mainland of Eastern Asia 

 Euptelea 

 Helwingia 

 Hosta 

 Hovenitt 

 Peracarpa 

 Tricyitis 

 Weigela 



Actinidla 



Ainsliaea 



A\ebia 



Aucuba 



Cercidiphyllum 



Cryptomeria 



Damnacanthus 



Deutzia 



Genera Found in the Temperate Flora of Japan with Outlying 



Taxa Extending Across Asia, Some into Europe 

 Adenophora Hedcra 



Adonis Ilex 



Botkriospermum Pseudostellaria 



Kengia Syringa 



Eranthis Thelygonum 



Forsythia 



The relationship of the flora of Japan to that of North Amer- 

 ica, especially eastern North America, was first elucidated by 

 Asa Gray in his now classic paper published in the Memoirs 

 of the American Academy of Arts and Sciences (see footoote 

 p. ix). Gray first elcuidated the close affinities that exist be- 

 tween the two areas. This floristic relationship is now explained 

 on a historical basis of a former land-bridge connection be- 

 tween Asia and North America across the Bering Sea in pre- 

 glacial times. Most of the American representatives of genera 

 common to both areas are considered by most authors to be 

 distinct from those in Japan, but in some instances the Ameri- 

 can and Japanese taxa may be distinguished only with diffi- 

 culty. 



Genera Common to Japan and Eastern North America 



Apios 

 Boy\initt 



Bucl{leya 



Caulophyllum 



Clethra 



Croomia 



Cryptotaenia 



Diarrhena 



Diphylleia 



Epigaea 



Hamamelis 



Ilea 



Leucotkoi 



hespedeza 



Magnolia 



Meehania 



Menispermum 



Menziesia 



Muhlenbergia 



Osmorhiza 



Pachysandra 



Phryma 



Shortia 



Stewartia 



Tipularia 



Torreya 



Trautvetteria 



Tsuga 



Wisteria 



Zizania 



Relict Species of Temperate Japan, Whose Principal 

 Distribution is in Northern Korea, Manchuria, and Amur 

 Adenophora palustris Carex onoei 



Astragalus adsurgens Lilium callosuin 



Campanula glomerata Polygonatum inflatum 



Carex cinerascens Senecio flammeus 



Carex leiorhyncha Trigonotis nakflii 



Carex lithophila Triosteum sinuatnm 



Carex meyeriana Viburnum carlesii 



Carex neurocarpa 



The coastal areas of the Japan Sea side of Honshu, centering 

 around Hokuriku from San'in District as far north as the west 

 coast of Ugo Province, contrast rather sharply in climate with 

 areas of the Pacific Coast at the same latitude. The winters on 

 the Japan Sea side are considerably more humid than those on 

 the Pacific side with much more snow in the mountains and 

 along coastal areas. Coniferous forests of Abies, Picea, and 

 Tsuga are charasteristic of the Pacific side of the country. 



Endemic or Hokuriku Elements in the 

 Flora of Japan Sea Side 



Agrostis hideoi 

 Alnus fauriei 

 Berchemia longeracemosa 

 Calamagrostis jauriei 

 Calamagrostis gigas 

 Camellia rusticana 

 Carex aphyllopus 

 Chrysosplenium fauriei 

 Corydalis capillipes 

 Epimedium sempervirens 



Hamamelis japonica var. 



obtusata 

 Ilex leucoclada 

 Iris gracilipes 

 Pedicularis nipponica 

 Poa fauriei 

 Ranzania japonica 

 Tripteryginm regelii 

 Viola faurieana 



Several gigantic herbaceous plants are found in the wet 

 coastal areas of the Japan Sea side, the most common being 

 Petasites japonicus var. giganteus. Polygonum sachalinense , 

 Cacalia hastata var. orientaUs, Urtica platyphylla, Angelica 

 niatsumurae, A. edulis, A. ursina, and Filipendula \amtscha- 

 tica. 



In the mountains near the Japan Sea coast where winter 

 snows are deep, the alpine zone descends to a relatively low 

 elevation and the development of moors is a prominent aspect 

 of the high mountainous districts of this region. Among the 

 common species in wet alpine meadows are Fauria crista-galli, 

 Tofieldia japonica, Narthecium asiaticum, Phyllodoce aleutica, 

 Boy\inia lycoctonijolia, Scirpus caespitosas, Scirpus hondoensis, 

 funcus beringensis, Geum peniapetalum, Plantago ha\usanen- 

 sis, and Primula cuneifolia var. ha\usanensis. This mountain 

 flora appears to be most closely related to that of more northern 

 areas in Kamchatka and Alaska where snowfall is heavy and 

 the climate is moist. 



In the Hokuriku region of the Japanese alps where heavy 

 winter snow weighs down all shrubby vegetation, most of the 

 understory shrubs are nearly prostrate or at least decumbent. 

 The occurrence of broad-leaved evergreen shrubs in this re- 

 gion, such as Ilex leucoclada. Camellia rusticana, Daphniphyl- 

 lum humile, Cephalotaxus harringtonia var. nana. Ilex crenata 

 var. paludosa, is possible because of a protective covering of 

 deep snow in winter. Also found here are Chiliusichloa aqua- 

 tica and Diplaziopsis cavaleriana, both represented more widely 

 in the warm-temperate areas of western Japan. 



BOREAL REGION 



The boreal region of Japan is characterized by a coniferous 

 forest belt composed of Abies mariesii, A. homolepis, A. mayri- 



