4 University of Michigan 



Even on the highest dunes the soil a foot below the surface 

 is always moist and the dune flora is surprisingly luxuri- 

 ant. There is a splendid series of transition stages from 

 the xerophytic habitats of the beach and the fore-dunes, where 

 the evaporation is greatest, though subject to excessive varia- 

 tion, to the climax forest of beech and maple.^ The first plants 

 appear just above the line which is ordinarily reached by the 

 waves during strong on-shore winds : these plants are princi- 

 pally the sea rocket (Cakile edentula), species of Artemisia, 

 and Potent ilia anscrina. Close behind them follows the fore- 

 dune association, where, in addition to the beach plants, are 

 found the sand cherry {Prunus pumila) , the beach pea (Lathy- 

 ris maritiuia) , willows, milkweeds, and such grasses as Cala- 

 movilfa longifolia and Ammophila brcvilignlata Fernald (= 

 A. arcnaria of American authors). This is easily the best 

 developed of the bare-sand associations on the Sawyer Dunes, 

 and the plant associations found on the inland slopes of some 

 of the traveling dunes show some resemblance to it, consisting 

 chiefly of grasses and milkweeds, together with some creeping 

 vines. The last of the associations characteristic of the bare 

 sand is typified by the Cottonwood (Populns deltoides), 

 together with the puccoon {Lithospermwn gmelini) , various 

 species of wild grapes, the poison ivy {Rhus toxicodendron) , 

 and the plants of the fore-dunes. And here is found the 



^ The following papers dealing with the dune flora are of particular 

 interest : 



F)ilkr. G. D., 1917. The Vegetation of the Chicago Region, pp. 3-12. 

 University of Chicago Bookstore. 



Fuller. G. D., 1914, Evaporation and Soil Moisture in Relation to 

 the Succession of Plant Associations. Bot. Gas., 58: 193-234. 



Cowles, H. C, 1899, The Ecological Relations of the Vegetation 

 of the Sand Dunes of Lake Michigan. Bot. Gac, 27: 117, 169-202, 

 281-308, 361-391. 



