Arctic Plants : Geographical Distribution 117 b 



with the American, except by means of a former wider distribution in the polar 

 regions, which the species has reached, though only in Finmark; and judging 

 from the fact that the species is absent from Greenland and the entire arctic 

 coast of our continent, besides from Siberia, it would appear as if the species had 

 a dual origin, from one centre in Europe and from another one in America, 

 inasmuch as the environment is identical and it is associated with the same species 

 of the genus, with Moneses, and with Chimaphila. The occurrence of some of the 

 species of Pyrola, Moneses, and Chimaphila in eastern Manchuria, and extending 

 from there to Japan, and among these being several endemic species, seems to 

 indicate an important centre of the genus on the eastern coast of Asia. 



The widely distributed P- rotundifolia reaches the arctic region only in 

 Finmark and Russia since, according to Ledebour, the species has not been recorded 

 from arctic Siberia; it occurs, however, in Terra Tschuktchorum. The distribu- 

 tion- agrees remarkably well with that of P. secunda but, as may be seen from 

 the table (Table 6), P. rotundifolia is quite a variable plant, seven character- 

 istic varieties having been described; thus it appears as if the species is exception- 

 ally well established in various parts of the northern countries, rather than in 

 the southern. It is totally absent from Greenland and the arctic coast of the \ 

 American continent but is there replaced by a close ally, P. grandiflorq, which 

 by several authors has been considered as a mere variety of P. rotundifolia. 

 It does not seem improbable that P. grandiflora has developed from P. rotundi- 

 folia in the arctic environment, but in any case the former is unquestionably of 

 American origin as stated above, even though it has reached the northeastern 

 corner of Asia and the Altai mountains. 



With respect to the typical P. rotundifolia, its habitat is somewhat peculiar 

 since it may thrive just as well in Sphagnum bogs as in shady woods, notably 

 coniferous. The species seems to be rnore typically developed on the European 

 continent, besides in England and Scotland, than really in North America where, 

 however, it is accompanied by four varieties, endemic to this continent, and 

 the variety arenaria (Hudson bay), known also from Greenland, Finmark, and 

 south to Germany. The prevalence of the varieties on this continent may 

 indicate an American centre of distribution of the species and at the same time 

 the gradual disappearance of the type. A similar case is exhibited by the occiu-- 

 rence of the species in arctic Norway, where three varieties: arenaria, pumila, 

 and bracteosa have been observed, and of these the variety pumila has also been 

 collected in eastern Siberia. In other words, we have in the P. rotundifolia- 

 alliance a series of types, some being characteristic of arctic Europe, others of 

 the American continent south of the arctic circle, and one, P. grandiflora, 

 especially characteristic of arctic America and Greenland. And it is quite inter- 

 esting to notice that of these types the arctic P- grandiflora has also become 

 distributed to Terra Tschuktchorum and Altai. 



The remaining species: P. elliptica, P. media, P. picta, P chimaphiloides, 

 and P. aphylla, are mostly of a somewhat restricted occurrence. However, 

 the distribution of P. elliptica comprises Newfoundland to British Columbia, and 

 through the northern Atlantic states to the mountains of New Mexico. The 

 species thus represents one of the members from the American centre of the 

 genus; although absent from the northeastern corner of Asia, the species, never- 

 theless, has extended to Japan. P. media is a genuine European type, which 

 has reached the arctic region of Norway, besides Iceland, together with P. minor 

 and P. secunda; toward the south it has become distributed to the Alps of 

 Switzerland and Caucasus. Pyrola pictd and P. aphylla, on the other hand, are 

 mainly western types, especially the latter; finally, P. chimaphiloides is known 

 so far only from British Columbia. 



In connection with these geographical notes may be mentioned that Pyrola 

 aphylla is only apparently "aphyllous"; it develops, as a matter of fact, two 

 kinds of aerial shoots, viz.: some that are terminal and bear a small rosette of 

 green leaves preceding the inflorescence, and others which are lateral and develop 



