— 22 — 



fectly evident, from what has been said, that between Lastrcea 

 and Phegopteris, Nephrodium and Gojiiopteris, there is abso- 

 lutely no distinction beyond the presence or absence of an in- 

 volucre ; and that in a large number of instances it is utterly im- 

 possible to decide whether the sori originally have involucres or 

 not. Is it worth while to maintain a distinction that is honored 

 almost as often in the breach as in the observance ? By the re- 

 adoption of Dryopteris the distinction between peltate indusia 

 and kidney-shaped indusia has been practically broken down as 

 a generic distinction. Why not, then, do away with the barrier 

 created by an indusium, when it prevents the formation of nat- 

 ural groups ? For, as I understand it, this is what modern botany 

 is striving for continually — the grouping together of plants whose 

 natural modes of growth and natural affinities shqw that they are 

 more or less closely related. In order to bring this about among 

 the ferns, I believe that we must lay aside some of the ancient 

 traditions of the order, ignore to a certain extent the old di- 

 visions of "involucrate " and " ex-involucrate "—ignore possi- 

 bly the shape of the sorus itself, as in a certain section of Gym- 

 no gramme — and rearrange the species according to their natural 

 affinities. Let us see to what result that would bring us in the 

 tribe AspidiecE. 



In the first place, there is no more distinct and natural group 

 among the ferns than that which was designated by Roth, Schott 

 and Presl as Polystichum. So true is this that the " polystichoid 

 habit" has come to be as well known among pteridologists as the 

 "lomarioid habit," or the " pteroid habit," and I cannot see why 

 it is not as much entitled to generic rank as any other strong, 

 natural, distinctive growth. Here also, as in Dryopteris, we find 

 a few species classed with Phegopteris simply because no indusia 

 are evident with their sori, but the natural habit is so strongly 

 polystichoid that no one would hesitate to place them in Poly- 

 stichum who was not hampered with the idea that the. presence 

 or absence of' an indusium is a fundamental principle of the 

 science. I would make Polystichum a full-fledged genus, and 

 would remove to it the polystichoid species of Phegopteris. As 

 thus constituted, the genus would contain about sixty-three 

 species. 



Next I would make the genus Dryopteris cover all those 

 species included by Hooker in the free -veined section of Nephro- 

 dium and designated as the sub-genus Lastrcea ; and would re- 



