THE WOODSIAS. 97 



Woodsias, the indusium is fixed to the frond underneath 

 the sorus. In the beginning, it surrounds the sporangia, 

 but early splits into several segments which spread out 

 in star shape when the sorus considerably resembles a 

 small green flower, the indusium answering to the corolla 

 and the sporangia to the essential organs. 



The range of the obtuse Woodsia is almost wholly in 

 the United States. One station in Nova Scotia is all 

 that is known beyond our limits in the East. Southward 

 it extends to Georgia, the Indian Territory and Arizona. 

 It is also reported from British Columbia and Alaska. It 

 may occur on any shaded ledge but it is not always to 

 be found in what appear to be suitable situations. It 

 is usually less common than its counterpart, Cystopteris . 

 fragilis. In the southern part of its range, the fronds 

 are evergreen but their texture would indicate that this 

 condition does not prevail northward. A small and 

 more glandular form has been described as the variety 

 glandulosa. The common form in fruit is illustrated in 

 the Key to the Genera. 



In the West the obtuse Woodsia is represented by 

 two other species which are occasionally found as far 

 east as northern Michigan. The first of these, Woodsia 

 Oregana, is chiefly distinguished by its narrower blade 

 covered beneath with flattened hairs and stalked glands, 

 its oblong-ovate, toothed pinnae and the much narrower 

 segments of the indusium. The second species, Woodsia - 

 scopulina, has shorter, nearly smooth fronds, with tri- 

 angular-ovate pinnae the lowest of which are noticeably 

 shortened. The indusium, which consists merely of a 

 few hair-like divisions, is difficult to see in ordinary speci- 

 mens. In appearance and habitat, both species are 

 much like the obtuse Woodsia and at various times have 

 been described as varieties of it. 



