American Fern Journal 
Vol. 1 APRIL 1911 No. 4 
The Pteridophyta of the arctic regions 
CARL CHRISTENSEN 
The number of species of Pteridophyta growing in arctic 
regions is larger than one should imagine judging from 
the unfavorable climatic conditions of these regions. Still 
it must be remembered that the arctie regions north of 
the forest region of the Old and New World measure mil- 
lions of square kilometers of very different nature, and 
one need not wonder that within such a vast area certain 
places are found where ferns can grow. Such places are, 
however, few and confined to certain smaller areas. — 
immense tundras of North America and North Asia are 
practically without true ferns, while some species of 
Equisetum and Lycopodium there find ee favorable : 
habitats, the former in the numerous marshes : 
places, the latter in the drier hesths of the slopes of the 
more land among 
a “Quite different as to climatic 
“Pacifie ar Bering 3 ae : 
ae Strait, and the broad broad n Gret 
“4 
