Arctic Plants: Geographical Distribution 93 b 



f ullertonensis, deserihed from specimens collected at FuUerton, in the Hudson 

 bay region, was also found on the arctic coast by the expedition; the specific 

 name is thus one of the numerous instances that prove geographic names to be 

 misleading, and such names ought always to be avoided. 



As to the southern distribution, S. reticulata has found its way to the Alps, 

 the Pyrenees, the Rocky mountains (Colorado); it occurs also in the Altai 

 mountains, from where S. glauca and S. arctica have also been reported. 



_ While thus the representation of the genus Salix, as it occurs in the arctic 

 region, is well exemplified by the collection brought home by the expedition, it 

 seenis very strange that the common arctic S. herbacea L. is not among the 

 species. This species is, as a matter of fact, reported from several stations 

 in the "American archipelago, and it is very common in Greenland, between 

 Lat. 60° and 76° 7' on the west coast, and at about 72° 25' on the east coast 

 (Dus6n); furthermore, it is known from Iceland, Spitzbergen, Scandinavia, 

 arctic Russia, Siberia (Obdorsk, collected by Sujef according to Pallas), but it 

 is absent from the coasts of Bering strait. Further south S. herbacea occurs in 

 Labrador, extending from there to summits of the higher Rocky mountains, 

 from Canmore, Alta., to the Selkirk mountains (Lat. 51°) in British Columbia; 

 in Maine it has been found in the alpine region of Mount Katahdin, and in New 

 Hampshire on Mount Washington. In South Europe it occurs in the Alps and 

 Pyrenees, and in Asia it has reached the Altai mountains. 



The distribution of S. herbacea thus agrees so well with that of S. reticulata 

 that it was really to be expected that the species would also be found on the 

 arctic coast. 



Considering, however, the species of Salix, represented on the coast, and 

 comparing their general distribution throughout the northern hemisphere, it 

 appears as if the genus has a most important centre of distribution in North 

 America, and especially in the arctic region. Undoubtedly the circumpolar as 

 well as several of the other arctic species originated in these regions, and as we 

 know from the writings of Nathorst,i S. polaris, S. reticulata, and S. herbacea 

 once inhabited the lowlands of Central Europe, associated with Betula nana, 

 Diapensia, Andromeda, Ledum, Oxyria, and several other genuine arctic plants. 

 In other words, they are members of the glacial flora, and some are still in exist- 

 ence on the southern mountains. 



One species of Populus was collected along the Hulahula river, Alaska, 

 and along the lower Coppermine river, Northwest Territories; the specimens 

 consisted of some dead leaves, and some wood and bark. Although the outline 

 of the leaves does not correspond with that of typical P. tremuloides Michx., I 

 have nevertheless "ad interim" referred the material to this species on account 

 of the structure of. the petiole, which corresponds with that of P. tremuloides, 

 it being very distinctly flattened. Owing to the possibility of the specimens 

 being P. balsamifera L., as the latter species is known to extend nearly as far 

 north, the following points relative to the distribution of both species may be 

 given. According to John Macoun (Catalogue, I.e. p. 456), Populus tremu- 

 loides Michx. is one of the most widely distributed of the deciduous trees. It is 

 found on all dry slopes from Newfoundland and Labrador throughout the 

 northern forest region to Alaska. It constitutes the "bluffs" and copse wood 

 scattered over the prairie region, and is a fine large tree in the southern part of 

 the sub-arctic forest. Southwards it extends through the northern States to 

 the mountains of Pennsylvania, northeast Missouri, southern Nebraska, and 

 through all the mountain regions of the west, often ascending to an elevation of 

 10,000 feet above the level of the sea, to the Sierras of central California, northern 

 Arizona and New Mexico, the high mountain ranges of Chihuahua, and San 

 Pedro M4rtir mountain in lower Cahfornia. (Sargent: Silva. Vol. 9, Boston, 1896) 



1 Nathorst, A. G. Uber den gegenwartigen Standpunkt unserer Kenntniss von dem Vorkommen 

 fossiler Glacialpflanzen. (Bih. K. Sv. Vet. Akad. Hdlgr. Vol. 17, No. 5. Stockholm, 1892.) 



