THE SENSITIVE AND OSTRICH FERNS. 255 



is so very fugacious that it is seldom seen by any save the 

 inquisitive scientist. It is hood-shaped, somewhat like 

 that of Cystopteris, and attached to the frond on the 

 inferior side of the " blackberry-like " sorus. It can be 

 found only in the youngest fronds. Part of a fertile 

 frond is shown in the Key 



At the approach of cold weather, the sterile fronds 

 wither but the fertile remain erect all winter. The latter 

 are most noticeable against a background of snow-clad 

 earth, but would never be taken for a fern by the ordi- 

 nary rambler. The berries remain tightly closed through 

 the winter and the sporecases commonly do not release 

 their spores until spring. Even then the fronds do not 

 fall. It is easy to find plants with fertile fronds of three 

 seasons still in place. The spores promptly germinate in 

 spring. 



The origin of the common name is involved in some 

 obscurity, and several ingenious theories have been ad- 

 vanced to account for it. One suggests that it has refer- 

 ence to the fact that the frond withers so soon after being 

 cut ; another that it is because the fronds are sensitive to 

 autumn frosts. Eaton says that the young fronds are oc- 

 casionally cut down by late spring frosts, but this is not a 

 common occurrence. There is still another theory which 

 accounts for the name by the assumption that the grow- 

 ing fronds wither if touched by the human hand, but 

 withstand the touch of other bodies. The German 

 botanist, Sprengel, is quoted as having proved this by 

 numerous experiments, and in Britten's " European 

 Ferns " we read that "the barren fronds are so thin and 

 delicate in texture that they will wither, even when grow- 

 ing, if drawn once or twice through the hand." Those 

 who are acquainted with our plant, will no doubt wonder 



