i 7 o THE ROCK SPLEENWORTS. 



reply that though widely scattered, in no case is its habitat 

 exactly like that of its supposed parents ; for while the eb- 

 ony spleenwort grows at the tops and bases of cliffs, and 

 Camptosorus grows on the shelving sides of mossy rocks, 

 >Asplenium ebenoides prefers the niches under overhanging 

 ledges. In addition, the processes of reproduction in 

 ferns are such as to afford very small chance for hybridiza- 

 tion. If, following Lowe's successful experiments in 

 crossing ferns by sectioning the prothallia and bringing 

 the antheridia of one fern in contact with the archegonia 

 of another, we could produce a plant like ebenoides from 

 the sectioned prothallia of its supposed parents, the fact 

 of its hybridity might be regarded as proven. Exper- 

 iments are being made in this direction at present, but 

 until we have definite results, it seems better to consider 

 this a distinct species. 



In outline the fronds are much like those of the pin- 

 natifid spleenwort, but are not easily confused owing to 

 the fact that the pinnules are thinner, narrower, longer 

 and pointed. The blade tapers from a broad base to a 

 slender tip and is fully pinnate below and deeply pinnat- 

 ifid above. There is great diversity in the shape and 

 arrangement of the pinnules, however. Some are eared 

 on one side, some on both, others not at all but are at- 

 tached to the rachis by a broad base. The pinnae are very 

 unequal in length, the longest often standing next to one 

 that is merely a short green ear. Some fronds, which 

 appear to be juvenile examples, have a broad blunt apex 

 and the lower portion merely toothed or lobed. In this 

 feature of producing some fronds without tapering tips, 

 it resembles the walking fern. The figure in Eaton's 

 "Ferns of North America" does not much resemble 

 average specimens. Like the pinnatifid spleenwort, this 



