400 PRINCIPLES OF BOTANY, ETC. 
as he does not value. To those belong principally 
the mosses, for which forresters and farmers care 
less than they ought todo. Sociable mosses are, 
Sphagnum palustre; Dicranum glaucum; Polytri- 
chum commune, &c. Solitary, are, Polytrichum pi/i- 
ferum; all the species of Phascum, Weissia palu- 
dosa, and many others, 
§ 364. 
Plants are, like animals, confined to certain cli- 
mates and latitudes. Several of warmer climates 
by degrees become accustomed to our climates, and 
even to much colder ones. The herbaceous plants, 
particularly, are sooner accustomed to a cold than. 
to a temperate climate. For in cold climates, with 
the beginning of winter a great-fall of snow mostly 
_occurs, which does not melt before the return of 
spring, when no more night frosts are to be dreaded, 
and which is only one degree colder than the freez- 
ing point. In temperate climates, on the contrary, 
it often freezes very hard without the least fall of 
snow, and this naturally destroys all plants. ‘Hence 
it is that Polar and Alpine plants with us are fre- 
quently frozen, where sharp frosts without snow are 
a common occurrence; whereas, these plants in thejr 
native countries are protected by the snow. Those 
herbaceous and annual plants of warm climates only, 
which want a longer period for the evolution of 
their sprouts and blossoms, than the short summer 
of cold climates allows them, or such as want a very 
great degree of heat, cannot be brought to live in the 
open air in these cold climates, 
a ulees 
