276 



OHIO BIOLOGICAL SUEVEY 



Later in tlie siumner the places of these are taken by another set 

 of plants, including: 



Cimucifufia rcfemosa (fi^. 15) Circaea lutetiana 



Phyrma leptostachya Aster divaricatus 



Adicca pumila Aristolochia serpentaria 



Saiiic'uhi C(rad('iisis Medeola rirf/iiiica 



Fis;. 15. Black Cohosh (Cimut-ifuga in tlie Liriodendron Forest. 



C'lilorophylU-less phanoganis are represented in abundance by the 

 parasitic Squaw-root, ConophiiUis America nu, and Beech Drops, Lep- 

 tamium Virginia na, and the saprophytic Monotropa uniflora and Hy- 

 popytis Americana. 



These Liriodendron "coves" once covered a large proportion of the 

 northern section of our area. I^elow Clear Creek they are, and probably 

 always were, scarce. Their place is taken almost everywhere by the 

 hemlock forest which, as has been stated, does not extend north of that 

 point. 



B. The Upl.vnd Forest 



The succession of associations in the ui)land forest is be.st seen by 

 ascending the point of one of the long, narrow ridges between the 

 ravines and walking back from the edge of the clitf through the pine 

 woods into the oak forest and around to the head of ilip ravine where 

 the upland merges with the lowland. 



TJic Cliff Top. At the tops of tVie cliffs there is a narrow strij) 

 of what may be termed a miniature lielu^n tundia (tig. 16), since it 

 possesses all of the essential features of the northern tundra. The sub- 

 stratum is extremely acid to litmus jiajx-r. It is exposi'd to the extreme 



