268 THE WALKING FERN AND HARPS-TONGUE. 



A form called intermedia has been described from Iowa. 

 In this the fronds are without ears at base and taper to 

 the stipes, in which characteristic they resemble the Old 

 World species, C. Sibericus. This latter inhabits northern 

 Asia and Japan and is the only other species in the genus. 

 The word Camptosorus is derived from two Greek words 

 meaning bent and fruit-dot and refers to the lines of 

 crooked sori. 



The Hart* s-Tongue. 



There can be no difference of opinion as to which is 

 the rarest fern in Northeastern America. This distinc- 

 tion is well known to belong to the hart's-tongue (Scolopen- 

 drium vulgare). So far as known, two limited regions in 

 the United States and two in Canada are the only ones in 

 the Western Hemisphere in which it grows. On the 

 other side of the world, however, it is abundant and 

 Shirley Hibberd includes it among the four commonest 

 species about London. 



It was first discovered in America near Syracuse, N. Y., 

 by Frederick Pursh who writes that he found it " In shady 

 woods in the western part of New York, on the planta- 

 tion of J. Geddes, Esq." It was afterward found in 

 greater abundance at Chittenango Falls and this place 

 is frequently named as the original station, but the re- 

 cent rediscovery of Pursh's station for it has set the 

 question at rest. At Chittenango Falls, the plants are 

 plentiful, growing on the talus at the base of a limestone 

 cliff, where the atmosphere is constantly moist from the 

 spray of a nearby waterfall. 



The fronds spread outward in a circular tuft and are 

 about half erect. They are dark, glossy green above, 

 somewhat lighter beneath, and very thick and leathery. 



