Polunin • Aspects of Arctic Botany 59 



and water lying to the north poleward cordingly, for the past 1 5 years or so, 

 of an imaginary line delimiting it from I have been gathering material for an 

 the subarctic regions, and which, as illustrated circumpolar treatment of all 

 astronomical lines of division fail, the species of seed plants and ferns, 

 seems best based on a set of biological etc., which are known to live in any 

 as well as climatological criteria. This arctic area. It does not profess to be 

 arctic-subarctic boundary may for the exhaustive, for I do not think a critical 

 present be drawn along whichever of arctic flora should be attempted with- 

 the following means of separation lies out more Russian materials than are at 

 farthest north in each narrow sector present available in the herbaria of 

 of the northern hemisphere: (1) a America and western Europe. Included 

 line 50 miles north of the northern are about 900 species belonging to 229 

 limit of coniferous forest, or at least of genera in 65 families. Doubtless further 

 more or less continuous taiga (that is, collecting, especially near the southern 

 terrain of sparsely scattered trees); (2) boundary of the Arctic, will add con- 

 north of the present limit of micro- siderably to these figures, 

 phanerophytic growth (that is, of trees 



2-8 meters in height, but disregarding arctic ecology and vegetation 

 straggling bushes in unusually favorable 



situations); or (3) north of the Norden- Let us next consider the ecological 



skiold line, which is based upon the and allied fields which are entering 



mean temperature of the warmest and more and more into the studies of 



coldest months of the year and is ar- arctic plant life. Whereas the flora of 



rived at by using an empirical formula, an area is made up of all the different 



kinds of plants inhabiting it, the vege- 



ARCTic FLORiSTic BOTANY AFTER 1900 tatioTi is conccmed largely with the 



question of the relative abundance of 

 Among the tendencies aiding re- these various kinds, and is the total dis- 

 search that have been growing in recent play made by the plants collectively, 

 years, especiallv with the post-war easy while their ecology is their relation- 

 transportation,' has been the admirable ship to the environment in which they 

 urge of specialists to visit the Arctic live. The environmental conditions in 

 regions themselves. Thus nowadays all the Arctic are usually especially rigor- 

 sorts of qualified men are available who ous, so that the inhabiting species tend 

 can expertly collect and describe the to be few, the individuals reduced in 

 many species. For example, in the study stature, and the ecological relation- 

 of the lower plants, such as Algae, ships frequently critical. 

 Fungi, Mosses, and Lichens, specialists Ecological studies have come well 

 in particular groups work in the field into their own in recent years, so that 

 investigating the various members we now have available numerous and 

 properly. widespread accounts of diff^erent arctic 

 Meanwhile there has long been an vegetation types. Much the same is 

 increasingly urgent need for a synthe- true of plant sociology', the study of the 

 sis of the taxonomic and phytogeo- composition of the communities that 

 graphical knowledge of the 'higher collectively form vegetation. Many 

 plants inhabiting Arctic regions. Pre- more accounts await the tedious study 

 vious attempts, most notably Ostenfeld in herbaria and work in laboratories to 

 and Gelert's Flora Arctica, have been support the field obscrA-ations. Unfor- 

 largelv abortive; moreover, recently our tunately, the study of the ecology' of 

 knowledge has grown enormously. Ac- individual forms has not been stressed 



