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contact with the soil is sufficient ])rotection, save in the most extreme cases. 

 These jihints. therefore, while not strongly developed in the upper beach, 

 are rarely wanting on active dunes. The willows commonly found are 

 /S. Yuviatilis, gloucophyila and adenophyUa. The dogwoods are G. stol- 

 imifcni and Buileiji. TJie i)oplar is the cottonwood, P. deltoidcs. To the 

 hotanlst. the adaptation of these plants for such a position are self-evident, 

 but individual cases present continual variations. Nothing could more 

 cleaiiy ilhistrate the extreme ])lasticity ot these shrubby species than their 

 quick and sure response to these constantly varying factors. 



These grasses lead in the attack upon the dunes. These 

 plants all arise from a single root stock. 



In the case of the grasses, which are chiefly Aiidropogon. scoparius, 

 Aiiiiiiophila areiHiria, Chthniiovilfa longlfoUa, and Elcijm us canadciifiifi, there 

 is a quick setting of roots from the nodes when there is but a partial sub- 

 mergence, while the long, horizontal branching root stock is constantly 

 sending up new stools during the continuance of favorable conditions. The 

 first plants to obtain a loothold uj)on these shifting sands are usually the 

 grasses. From a single stool through the agency of the root stock there is 

 a rapid spread which covers a very considerable area. In various places 

 upon the most active portion of the dunes some one or more of these grasses 

 obtain a foothold and struggle fiercely to maintain the place they have 

 seized. So far as my personal observations go, the iuvasi(m of the dune is 



