Winslow: Double Sori in Athyrium 



89 



Fig. 1 and 2. Double sori in A . felix-femina and .4. auguxtifolium. 



vein that forks about in the middle of the attachment 



of the sori, and the third on an unforkcd vein, a real 

 double sorus. 



A few years ago authors generally regarded A. filix- 

 femina as our only representative of the subgenus Athy- 

 rium. Underwood and Maxon included also A. thelyp- 

 teroides, and later, others, including the editors of the 

 current revision of Gray's Manual, following Milde's 

 description, involving the character of the stipe and 

 venation as well as the sori, have made A. angustifolium 

 a third Athyrium. The variety of opinion is further indi- 

 cated by the fact that A. filix-femina has had, in the 

 course of its varied career as an object of scientific study, 

 such generic names as Nephr odium and Aspidium, and 

 that A. thelypter crides, or achrostichaides as some of us 

 prefer to call it, has been called Diplaziiim thelypteroides. 



All these genera have been chiefly characterized by 

 the form of the sori and indusia. A straight indusium 

 extending along one side of a veinlet is said to be asple- 



