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HISTORY OF BRITISH FERNS. 
family. The Alpine Woodsia, like its congener, grows in 
a tufted manner, sending up several fronds from the crown, 
from the base of which the dark-coloured wiry roots are 
protruded. In form these fronds are longish and compara¬ 
tively very narrow, almost linear, as it is termed ; and they 
are pinnately divided into several roundish triangular pinnae, 
which are shallowly lobed on the margin, and are usually 
set on alternately along the opposite sides of the stalk or 
rachis ; those towards the lower part are usually placed at 
a greater distance apart than those near the upper end. 
They are nearly smooth on the surface, and, in this respect, 
unlike those of the kindred species, which have a much 
more hairy appearance ; small hair-like scales, in company 
with hairs, are however present in this species. The mid¬ 
vein of the pinnae is indistinct, and throws out veins 
into each lobe, these veins being more or less branched 
according to the size of the lobes. The sori are placed 
near the extremity of the veins, and are often abundantly 
produced, so as to become crowded on the pinnae. 
The Alpine Woodsia is also named W. hyperborea, and 
formerly Acrostichum alpinum, Acrostichmn hyperboreum, 
Polypodium hyperboreum, and Polypodium arvonicum. 
The two species of Woodsia are, in Great Britain, found 
