Ferns of the Woods 



fail to mark the Common Prickly Shield Fern. It 

 belongs to the genus Aspidium, which is often confused 

 by the beginner with the genus Nephrodium. The 

 latter genus had the indusia, as we have seen, kidney- 

 shaped, while the Shield Ferns, the name given to all 

 ferns belonging to the genus Aspidium, have circular 

 but unnotched indusia, attached by short stalks from 

 their centres to the under surface of the frond. This 

 method of attachment is described as "peltate." Thus 

 we say the distinguishing mark of the Shield Ferns is 

 globular sori, covered by circular and peltate indusia. 

 We may find the fern we are in search of at the border 

 of the wood partially sheltered by the trees. 



The rootstock from which the fronds spring in tufts 

 is unusually stout, and the leafstalks and midribs are 

 thickly clad with rusty scales. The fronds which are 

 often from 2 to 3 feet in length are lanceolate in outline, 

 dark green in colour, and shining or glossy on the 

 upper surface. They are bipinnately divided, the pin- 

 nules nearest the principal midrib showing an ear-shaped 

 enlargement on the side nearest the midrib of the pin- 

 nae. These pinnules which are furnished with rather 

 sharp, prickly teeth can hardly be said to be stalked, 

 being rather what botanists call decurrent that is, not 

 attached by a stalk, but by their base, which is prolonged 

 downwards. There are two varieties of this fern, but 

 as so good a botanist as the late Sir J. D. Hooker 

 jhesitated to rank them as species, we may omit them 

 jfrom .our list of woodland ferns. 

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