S4 JOURNAL OF THE ARNOLD ARBORETUM [vol. i 



by Japan in 1910. Since that date the Government-General has systemat- 

 ically undertaken an investigation of the natural resources of Korea and the 

 botanical work is in the hands of Dr. T. Nakai. So far 2,8^2 species, vari- 

 eties and forms, belonging to 780 genera, rejiresenting 151 families, have 

 been recorded, but the work is by no means completed. About one-fourth 

 of these are woody. Most of the families which occur in Japan, north 

 China and northeast Asia are present but often much reduced in numl)er 

 of representatives. For example:— the family of Magnoliaccae is repre- 

 sented by two genera (Magnolia, Schisandra) with three species. Tlie most 

 prominent family that is missing is Ilamamclidaccac. A genus that one 

 might expect to l)e present and which is not is Cercidiphyllum. 



Now whilst the seas are natural phytogeograj)hical barriers the political 

 boundaries of Korea, — i.e. the Yalu and Tumen rivers and the Paiktu moun- 

 tains — are not and the flora is essentially part of that of the great region 

 of northeast Asia including Manchuria and the northernmost i)arts of China 

 proper as far west as Mt. Wutai in Shansi province. Of woody j^lants at 

 least one genus (Pentactina) and a limited number of species {Vihurnuvi 

 Carlesii Hemsh, Cornus officinalis S. & Z., Forsyihia ovata Nakai and a few 

 others) are endemic, quite a number such as Abies fiolophylla Maxim., Rho- 

 dodendron Schlippenbachii Maxim, do not cross the Yalu watershed to the 

 plains of Manchuria, but the majority are widespread on the continent of 

 northeast Asia and many cross to Hokkaido and to northernHondo in Ja])an 

 proper. Of the latter mention may be made of Alnus japonica S. & Z., 

 Rhododendron hrachycarpinn G. Don, Styrax ohassia S. & Z. Further, a few 

 species, including five {Querciis glandulifera Bl., Q. aliena BL, Q. dcntata 

 Thunb., Q. serraia Thunb., Q. variabilis Bl.) of the six species of deciduous 

 leafed Oaks, are widely distributed in China and Japan. The two volcanic 

 islands, Quelpaert off the extreme south, and Dagelet off the east coast, in 

 the Japan Sea, are peculiar. The first-named, with its peak, Hallai-san, 

 1952 m. high, has largely a Japanese flora, and is marked by the presence of 

 broad-leaf evergreens in great variety. A few species, for exami)le, Maackia 

 Faiiriei Nakai, are possibly endemic and pure woods of Hornbeam {Carpimis 

 laxiflora Bl. and C Tschonoskii Maxim.), with Daphniphylhnn macropodum 

 Miq. and Taxus ciispidata S. & Z. as conspicuous undergrowths are a char- 

 acteristic feature between 1000 m. and 1300 m. Such woods arc unique in 

 the Orient. The trifoliolate Orange {Poncirus trifoUaia Raf .) is indigenous, 

 growing in the beds of torrents or among boulders; nowhere else in my 

 travels have I seen this plant truly wild. No species of Spiraea, Deulzia nor 

 Philadelphus grows on Quel])aert, yet they are conmion shrubs on the 

 mainland. On the other hand. Hydrangea petiolaris S. & Z., Schizophragma 

 hydrangcoides S. & Z. and Ostrya japonica Sarg., unknown on the mainland, 

 are common on this island. Two other verv common i)lants are Rhodo- 

 dendron Weyrichii Maxim, and R. poukhanense Lev.; the first named does 

 not grow elsewhere in Korea whereas the latter is widely spread through 

 the peninsula. Such typical Japanese trees as Pinus Thunbcrgii Pari., 

 Torreya nucifera S. & Z., Myrica rubra S. & Z. and Machilvs Thunbcrgii 



