Jennings : A Botanical Survey of Presque Isle. 385 



in humus and constituting altogether a very favorable habitat for cer- 

 tain weeds. 



The structure of this formation is typically as follows : 



Fades. — 



Solidago canadensis, Meiboniia canadensis. 



Principal Species. — 



Anemone canadensis. 

 Secondary Species. 



Lactuca canadensis, Melilotus officinalis, 



Strophostyles helvola, Trifolium pratense, 



Trifolium repens. Ranunculus abortivus, 



Poa compressa, Vitis vulpina, 



Plantago lanceolatus, Mentha piperita, 



Mentha cardiac a, Carduus arvensis, 



Erechtites hieracifolia, Xanthitan commune, 



Barbarea barbarea. 



In certain respects the formation resembles a roadside formation. 

 In a few spots a thin sod has formed, composed of Poa compressa. 

 During early summer, June, there is an aspect characterized by the 

 Anemone canadensis society, but the main mass of vegetation develops 

 later in the season, the facies becoming most conspicuous in late 

 summer and early fall. 



In X and Y (see map) and along the bay-shore to the Chimney 

 Ponds including T also, the vegetation is in a much more highly de- 

 veloped stage, owing doubtless to the longer period in which it has 

 been allowed to develop undisturbed. The occasional incursions of the 

 lake through the narrow neck of the peninsula to the west since 1861 

 must have considerably disturbed, if not totally destroyed, the vegeta- 

 tion of the marsh along that shore, and as a consequence the vegeta- 

 tion there represents a younger stage than does the vegetation 

 farther to the west, where the development has been continuous and 

 undisturbed. 



The structure of the vegetation in the more highly developed marsh 

 is typically as follows : 



(a) Scirpus Formation, 



i^b) Phragmites-Typha Formation, 



((t) Cladium-Calamagrostis Formation, 



(rt^) Rhus-Alnus Formation, 



((?) Ulmus-Acer Formation. 



