52 



POLYPODIACEAE 



Athyrium 



Jan. 



Feb. 



Mar. 



Apr. 



May 



June 



July 



Aufc 



Sept. 



Oct. 



Nov. 



Dec. 



Miles 



50 



Map 27a 

 Afhyrium angustum 

 var. elatius (Link) Butters 



~^0 



Map 28 



Camptosorus rhizophyllus (L.) Link. 



2. Athyrium thelypteroides (Michx.) Desv. (Asplenium acrostichoides 

 Sw. and Athyrium acrostichoides (Sw.) Diels.) Silvery Spleen wort. 

 Map 25. Infrequent in southern Indiana, becoming rare in the northern 

 part. It prefers a moist, deep humus soil in ravines and protected places 

 in beech and sugar maple or white oak woods. 



N. S. to Minn., southw. to Ga., Ala., and Mo. ; also in Asia. 



3. Athyrium asplenioides (Michx.) Desv. Map 26. This species and 

 the next species and its varieties are the results of dividing an aggregate 

 that formerly had been designated as A. Filix-femina. For a detailed 

 study of this group see Butters' "Synoptical treatment of the Lady Fems 

 of Eastern North America" (Rhodora 19: 188-197. 1917). Butters has 

 gone into great detail in his study of the species and discusses "sun" and 

 "shade" forms. Some recent authors are disposed to regard some of the 

 forms as merely ecological variations. See Wiegand's comment on varieties 

 of the next species in "The Flora of the Cayuga Lake Basin," page 32. 1926. 

 Pinkerton in "Ferns of Missouri" (Ann. Missouri Bot. Gard. 20: 55. 1933) 

 says : "This species and A. angicstum are very difficult to distinguish. It is 

 often necessary to have the whole plant, fruiting and not too mature, to be 

 absolutely certain. I have taken the character of the spore as my ultimate 

 criterion." 



I can not satisfactorily separate the species and their varieties and 

 would not publish on them were it not that C. A. Weatherby has named 

 nearly every one of my specimens. I hereby wish to express my appre- 

 ciation of the difficult task of naming so many of my specimens of this 

 complex. 



Infrequent in the southern counties but frequent in its habitat. It 

 prefers a hard, white, moist, clay soil and is usually found in low, flat 

 woods associated with beech and sweet gum or sweet gum and pin oak. 

 It is also found in residual soil at the base of sandstone cliffs and in sand- 

 stone soil on wooded slopes. 



Mass., Ohio to Mo., southw. to Fla. and Tex. 



