Introduction 



ana, A. veitchii, Picea jezoensis, Larix \aempferi, Tsuga di- 

 versifolia, and Taxus cuspidata, which occurs at altitudes up to 

 2,000 m, in the western parts of Honshu and Shikoku. In the 

 central district of Honshu this zone occurs from 1,500 to 2,000 

 m, altitude. In the northern districts of Honshu the coniferous 

 belt is found from 1,000 to 1,500 m. altitude and to near sea 

 level in the eastern and northern parts of Hokkaido. Common 

 plants of this boreal region are: 



Acer tschonos\n 

 Alnns matsumurae 

 Alnus maximowiczii 



(upper zone) 

 Bettda ermanii 



Euonymus tricarptis 

 Oplopanax Japonicus 



Deciduous Trees 



Betida playtyphylla 

 Primus ssiori 

 Sorbus commixta 

 Sorbus matsumurana 



Deciduous Shrubs 



Salix reinii 

 Vaccinium yatabe 



Broad-leaved Evergreen Shrubs 



Ilex rugosa 

 Ilex sugerokf 



Rhododendron brackycarpum 

 Rhododendron degronianum 



Herbaceous Plants 

 Circaea alpina var. caulescens Maianthemum ddatatum 



Cornus canadensis Microstylis monophyllos 



Epdobium spp. Platanthera ophrydioides 



Glyceria alnasterettim Trientalis europaea 



Lianas 



Actinidia \olomikta 



Rhus ambigua 



Plants of Coastal Dunes 



Arabis stelleri var. 

 Artemisia stelleriana 

 Carex gmelinii 

 Elymus mollis 

 Glehnia littoralis 

 Honl^enya peploides 

 Lathyrus maritimus 



Chrysanthemum arcticum 

 Potentilla megalantha 



Linaria japonica 

 Matricaria matricarioides 

 Matricaria tetragonosperma 

 Mertensia asiatica 

 Rosa rugosa 

 Scutellaria strigillosa 



Plants of Sea Cliffs 



Trifolium Uipinaster 



Plants of Littoral Swamps in Coastal Areas 



Carex lyngbyei 

 Carex mackenziei 

 Glaux maritima 

 Salicornia europaea 



Scirpus planiculmis 

 Triglochin maritimum 

 Triglochin palustre 



Aquatics 



Nuphar pumilum Scirpus tahernaemontani 



Polygonum amphibium Sparganium gramineum 



Potamogeton heterophyllus 



Plants of Sphagnum Bogs 



Andromeda spp. 

 Carex curta 

 Carex limosa 

 Carex middendorffii 

 Drosera angelica 

 Drosera rotundifolia 

 Eriophorum spp. 



Ledum spp. 

 Narthecium asiaticum 

 Rhychospora alba 

 Scheuchzeria 

 Tofieldia japonica 

 Vaccinium oxycoccus 



Plants of Fresh-water Marshes and Stream-margins 

 Alnus hirsuta Polygonum sachalinense 



Calamagrostis langsdorffii 

 Epilobium angustifolium 

 Phragmites communis 



Salix spp. 

 Scirpus wichurae 



The genera found in the boreal region mostly are those with 

 a wide circumboreal distribution. Only Pteridophyllum, Dac- 

 tylostalix, and Tripetaleia are endemic of this floristic province. 



Coniferous forests are widely scattered in the high moun- 

 tains of the Japan Sea side, consisting, when they do occur, 

 mainly of Thuja standishii and Larix leptolepis. Deciduous 

 woody species predominate in the vegetation of this region, 

 include Acer tschonoskji, Alnus maximowiczii, Betula ermanii, 

 Hamamelis japonica var.. Magnolia salicijolia, and Sorbus 

 matsumurana. 



In lowlands, especially near the seacoast of eastern Hok- 

 kaido centering in the provinces of Nemuro and Tokachi, fogs 

 in summer are of frequent occurrence as a result of the cold 

 Kurile Current which flows southwestward along the south 

 coast. Moors in this area are well developed. Carex subspatha- 

 cea and C. mac\enziei occur in the littoral swamps, the only 

 areas where these plants appear in Japan. In the coastal area are 

 Saxifraga bracteata, Potentilla megalantha, Cochlearia oblongi- 

 jolia. Rhododendron parvifolittm, and Fritillaria camtschatcen- 

 sis, these having reached our area from farther north. 



ARCTIC-ALPINE REGION 



Extensive arctic-alpine areas are not represented in Japan, 

 although treeless tundralike areas of limited extent occur on 

 several mountain peaks scattered over various parts of the 

 country. In the central district of Honshu, the alpine zone 

 occurs at elevations of about 2,500 m. In the northern district 

 of Honshu it begins at about 2,000 m. and at 1,500 m. in Hok- 

 kaido. Characteristically, the alpine zone is represented by a 

 shrubby pine, Pinus pumila, except on the more recent vol- 

 canoes, such as Mount Fuji and Mount Asama. Immediately 

 below the Pinus pumila zone deciduous shrubs are prominently 

 represented, mainly Alnus maximotviczii, Betula ermanii, Prii- 

 nus nipponica, Vaccinium. uliginosum, V. axillare, Sorbus 

 sambucijolia, and S. matsumurana, mixed with many high- 

 altitude herbaceous plants. In the alpine zone, the plants con- 

 sist mainly of Ericaceae, Primulaceae, Caryophyllaceae, Gen- 

 tianaceae, Scrophulariaceae, Ranunculaceae, Rosaceae, and 

 Cruciferae. The genera of the alpine zone mostly are those 

 widely distributed throughout the northern parts of the North- 

 ern Hemisphere. The only endemic genus of the alpine area of 

 Japan is Japonolirion, found on serpentine rocks. Most of the 

 species of alpine plants found in Japan occur also in eastern Si- 

 beria, Alaska, the Aleutians, and Kamchatka, or represent 

 widely distributed circumpolar species. Very little relationship is 

 shown between the alpine plants of Japan and those of the 

 Sino-Himalayan area, although Polystichum lachenense (Fil- 

 ices) and the genus Androcorys (Orchidaceae) occur in both 

 areas. 



Recent vulcanism in Mount Fuji, Mount Asama, Mount 

 Iwate, Mount Chokai and in some other areas may be responsi- 

 ble for the occurrence of alpine species at lower elevations than 

 on nonvolcanic mountain peaks found elsewhere. 



Local endemism on Mount Hayachine, Mount Shibutsu, and 

 Mount Apoi is associated with serpentine rocks found on these 

 mountain peaks. The incidence of alpine plants is relatively 



