314 The Ohio Naturalist. [Vol. VIII, No. 6, 



here consists, then, of dissophytic annuals, constituting as de- 

 termined by the facies the Cakile-Xaiithium Formation: 



Facies: Cakile edeniula, 



Xanthium commune, ^^ 

 Polanisia graveolens. 



Principal Species: Strophostyles helvola. 



Secondary Species: 



Cenchrus tribiiloides, Euphorbia polygonijolia. 



There is considerable alternation ' in this formation, the 

 Cakile edeniula Consocies occupying the more exposed Lake 

 beach, while the Xanthium comfnune Consocies is best seen in 

 places along the less exposed Bay beach. Polanisia is more 

 indifferent as to its location, it occurring sometimes alone but 

 more usually indiscriminatel}' mixed with the other facies. 



The Sand Plain — The Artemisia-Panicum Formation. 



Where the continuity of the outward growth of the land form 

 of the peninsula has not been broken by the formation of a sand 

 ridge it is often difficult to draw the line between the upper limit 

 of the Drift Beach and the lower limit of the Sand Plain.*' Upon 

 the burial of the driftwood which accumulates in the upper part 

 of the Diift Beach by the indrifting of sand, the land becomes 

 sufficiently elevated to form a slightly different habitat which is, 

 of course, free from the mechanical violence of the waves at any 

 time, other than at very rare periods. The habitat thus may 

 support a vegetation of annuals, biennials, and perennials, de- 

 pending simply upon their ability to cope with the otherwise severe 

 conditions of environment. 



The vegetation of the Sand Plain mav, from its facies, be 

 designated as the Artemisia-Panicum Formation. It has essen- 

 tially the following structure: 



Facies: Artemisia caudata, 

 Panicum virgatum. 



Principal Species: 



Salix interior & var. wheeleri. 

 Arenaria serpyllifolia, 

 Arabis lyrata. 



16. This species is probably best denominated as Xanthium commune, 

 rather than as X. canadense, as given in the Flora of Cedar Point. — W. A. 

 Kellerman and O. E. Jennings. Ohio Nat. 4 : 186-190. June, 1904. 



17. Synonymous habitats with this are Macmillan's "Back Strand" 

 (Lake of the Woods); Cowles' "Upper Beach" (Lake Michigan); and 

 Ganong's "Grass Plain" (Miscou Island). 



