146 



here could be greatly extended by further observation. Only the 

 seed-plants, ferns, and fern-allies are included, and the usual habitat 

 of each species is given by associations. Many unusual locations of 

 species are omitted. The nomenclature follows the Vienna Code, as 

 exemplified in the seventh edition of Gray's Manual. 



Polypodiaccae 



Pteris aquilina L. Winnebago, Amboy, and Havana areas, in the 

 black oak association ; Kankakee area, very abundant in the black 

 oak forest and the intervening marshy meadows; sometimes persist- 

 ing as a relic in the bur oak association in the Winnebago area. 



Woodsia ohUisa (Spreng. ) Torr. Ocjuawka area, in the mixed 

 forest association, growing in dense shade on mats of moss on the 

 mesophytic portions of the river dune. Not observed elsewhere in 

 the sand region. 



Ophioglossaccac 



Botrychiiiiii tcniafiiiii (Thunb.) Sw., var. uitcrnicdium D. C. 

 Eaton. Winnebago area, in the upland portions of the bur oak as- 

 sociation. 



BofrychiiDii 7'irgiuiainnii (L. ) Sw. With the last species. 



Equiseiaccae 



Bqitiscfuiii arz'ciisc L. Dixon area, in the Solidago association 

 in extinct blowouts. 



Bquisctum hycmalc L. Oquawka area, an invader from the al- 

 luvial flood-plain vegetation into the mixed forest association on the 

 river dune. 



Bquisctum hycmalc L., var. intermedium A. A. Eaton. Han- 

 over, Dixon, and Havana areas, usually in the bunch-grass associa- 

 tion ; sometimes growing in dense masses and aiding in the stabiliza- 

 tion of blowout deposits ; abundant in the Solidago association in 

 the Havana area. 



Sclagiiicllaccac 



Sclagiiiclla rupcstris (L.) Spring. Hanover area, in the bunch- 

 grass association. It is frequently concerned in the fixation of sand 

 and the re-esta1)lishment of the bunch-grass, and sometimes appears 

 in the windward slope association of the blowouts. The growth rings 

 formed by this plant have been described in the text. 



