3^ JOURNAL OF THE ARNOLD ARBORETUM [vol, i 



Plconandrae which 1 have mentioned, but it is necessary to collect from 

 the same plant at different times, because only well-collected material will 

 be sufficient to make more definite statements possible. Besides this it is 

 very important that the collector make notes with regard to the habitat, 

 the habit, the associated species of Salix, and whether the branchlets are 

 more or less brittle or tough at tlie joint. The last character seems to be of 

 great taxonomic value for the separation of the tough-jointed Bonplandi- 

 anac from the very brittle-jointed yigrae and the (more or less) brittle- 

 jointed Liicidac and Amygdalinae. 



A rHYTOGEOGRArHICAL SKETCH OF THE LIGNEOUS 



FLORA OF KOREA 



E. H. Wilson 



Korea, or Chosen, as it is now designated by the Japanese, is a peninsula 

 bounded on the east })y the Japan Sea, on the south and west by the Yellow 

 Sea, and on the north by Manchuria and the Primorsk province of eastern 

 Siberia from which it is separated V)y the Yalu River, Paiktu mountains and 

 the Tumen River. Until quite recently it was styled the ''Hermit King- 

 dom" by peoples of western lands and it had little or no intercourse with the 

 outside world. The whole i)eninsula (including adjacent islands) is con- 

 fined within Lat. 33° 1^2' and 43° 02' N. and Long. 124° 13' and 130° 54' E. 

 and has a total area of 84,173 square miles (English). Geologically 

 speaking nearly four-fifths of Korea is of granites and highly metamor- 

 phosed rocks of Prc-Cambriau age. In the central parts between Lat. SS"" 

 and 40° X. and stretching almost from sea to sea is an area of Paleozoic 

 rocks, chiefly mud-shales, shites, and a little limestone; in the southeast is 

 an area of Mesozoic limestones with intrusive i)oq)hyritic rocks and isolated 

 outcro])i)ings of this combination of rocks obtrudes itself in other parts of 

 Korea. Basalt underlies nmch of the ])eninsula and in the volcanic areas — 

 Paiktu momitains, highlands south of Gensan, the islands of Quelpaert 

 (Sai-shu-to) and Dagclet (Ooryongt5) — it has been forced to the surface 

 and is surmounted by trachyte lavas. Each of these geological formations 

 has certain ])lants peculiar to it. For example, Larch {Larix dahurica var. 

 Principis-Rupprechtil Rehd. & ^Yils.) grows only on the recent volcanic 

 soils of the Paiktu region and there forms vast forests; a Birch {Bctida 

 Schmidtii Regcl), one of the most valuable of Korean hardwood trees, is 

 confined to the granites and metamorphic rocks; a Lilac {Syruiga dilainia 

 Nakai) is found only on the paleozoic rocks of north-central Korea. The 

 climate is the best in the Far East and the country is destined to become 

 the health resort of the Orient. It is essentially continental in character 

 but in the extreme south and east-southeast, near the coast it is moderated 

 bv the influence of the Ja])an current — a warm ocean stream similar to our 

 Gulf Stream. On Quelpaert Camphor and Orange trees grow at sea-level 

 and the temperature there seldom falls below the freezing-point; in the 



