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 (Hricacee, Empetrum) attractive to 
animals, or numerous small light seeds, or spores, easily 
spread abroad by the wind (mosses, grasses, Cruciferae, 
Caryophyllacee, Composite). 
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’ 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. 
