NATURAL AREAS AND REGIONS 



95 



cession of day and night. This factor 

 is equally important in the character, 

 distribution, and development of the 

 plant and animal life. Since all except 

 the southernmost point of the island 

 lies within the Arctic Circle, nearly its 

 whole extent has periods of continuous 

 sunshine and continuous nighfc. The 

 period without sunlight is six weeks 

 long in latitude 70 N.; thirteen weeks 

 in latitude 75 N.; and eighteen weeks 

 in 80 N. The period of continuous 

 sunlight is slightly longer. The sudden 

 development of the plant life, and the 

 rich life of the sea are in considerable 

 measure due, to this period of continuous 

 light. 



BIOTA 



Plant life 



The plant life of Greenland includes 

 some 400 species of vascular plants, 

 600 mosses, 700 fungi, 300 lichens, 500 

 algae, and 600 diatoms. More of the 

 lower species will doubtless be dis- 

 covered, but the list of vascular plants 

 is probably almost complete. The long 

 stretch of Greenland coast, through 

 varying physiographic and climatic con- 

 ditions, would suggest a richer flora than 

 that represented by only a few more than 

 400 species, even with the rigorous 

 arctic climate; but the flora is quite 

 post-glacial in origin, and since Green- 

 land is an island swept almost exclu- 

 sively by polar currents, and having its 

 nearest point of approach to other 

 lands at its northern extremity, where 

 conditions for plant migration are most 

 unfavorable, the immigration of plants 

 since the dispersal of the ice-sheet has 

 been exceedingly slow. 



The flora of Greenland offers some 

 interesting problems in distribution and 

 immigration. Some species are highly 

 localized. Some are European in rela- 

 tionship, some are American, and a 

 very few are endemic. Some are cir- 

 cumpolar high latitude species, some 

 are from the Canadian zone. How have 

 they come to Greenland, and how have 

 they established themselves? The an- 

 swer has been only partially given, and 



many a controversy has raged over the 

 solution of these problems. 



Fifty families of vascular plants are 

 represented in the Greenland flora, of 

 which the Cyperaceae, Graminae, Ca- 

 ryophyllaceae, Cruciferae, and Com- 

 positae are the largest. The genera 

 richest in species are Carex, Saxifraga, 

 Pedicularis, and Draba. Many of the 

 genera are represented by one species, 

 the average ratio of genera to species 

 being 2:5. The southernmost part of 

 the island about Cape Farewell has a 

 flora of almost 300 species; the Smith 

 Sound region almost 20 farther north 

 and within 15 of the pole, has almost 

 150 species. 



The entire island is beyond the north- 

 ern limit of true trees, and though 

 isolated small tracts far within the land 

 near the head of the fjords of the south- 

 ern west coast may bear a tree-like 

 growth of birch, willow, alder, and 

 conifers, the entire land is unforested, 

 Even well developed shrubbery is rare. 

 Generally all tree-growth and shrubbery 

 are dwarfed to creeping or prostrate 

 form alder, willow, juniper, vaccinium, 

 and birch. Even the arctic and alpine 

 forms are pauperate or dwarfed as the 

 northern reaches of the coast are 

 approached. 



The "Feldmark" is the most widely 

 distributed type of vegetation, the 

 first to appear on moraines from which 

 the ice has retreated, or wherever new 

 land appears to afford opportunity for 

 new plant growth. In this association 

 the plants are so far apart that the 

 spaces between are much larger than 

 the spaces occupied. The struggle is 

 not among one another, but against the 

 rigorous conditions. Among the plants 

 taking their place thus as pioneers are 

 the arctic poppy, a number of the saxi- 

 frages and cresses, dryas, some of the 

 cinquefoils, a number of the cresses, 

 and a few others. 



Where the soil is relatively dry the 

 heath-association covers the terrain. 

 It is composed of the small shrubs 

 junipers, Vaccinium, Salix, Betula, Cas- 

 siope, Empetrum, Dryas, Rhododendron, 



