THE FLORA 405 



Of fruits, the most common are such as depend on dis- 

 semination by wind or by birds and other animals. A few 

 species depend on other methods mainly, as in case of the 

 large easily floating bladders or pods of Oxytropis and 

 other legumes, or of large seeds that rarely find their way 

 far from the parent plant. But the families best repre- 

 sented in individuals, and largely also in species, are such 

 as bear small berries (Ericaceae, Empetrum) attractive to 

 animals, or numerous small light seeds, or spores, easily 

 spread abroad by the wind (mosses, grasses, Cruciferce, 

 Caryophyllacece, Compositce) . 



The regions of Arctic vegetation possess relatively fewer 

 species and varieties than more favoured localities, and most 

 of these are the same as those growing in the colder tem- 

 perate zones. As Hooker 1 points out, uniformity in 

 physical characters and absence of those changing con- 

 ditions which we assume to be stimulants to variation 

 (different combinations of conditions of heat, light, mois- 

 ture, and mineral characters) give uniformity in vegetation. 

 Hooker gives the total number of flowering species in 

 Arctic Europe as 616, in Arctic East America as 379, in 

 Greenland as 207. On the other hand, he estimates that 

 5800 species exist in temperate Australia. Gray's New 

 Manual of Botany (7th ed., 1908) enumerates about 

 4000 species of flowering plants and ferns, belonging 

 to over 150 families, from the central and northeastern 

 United States and Canada. But in Greenland, according 

 to Schimper, there are only 386 species of vascular plants, 

 belonging to 53 families. Labrador shows similarly a 



1 Joseph D. Hooker, Distribution of Arctic Plants. Trans. Linnean 

 Society, 1862, Vol. XXIII, p. 251. 



