188 MISSOURI BOTANICAL GARDEN. 



river deposit h 



the stems of the 



Sdix, Betula and Populus seedhngs, foniuiig a miniature 

 levcc, through the action of which the land lying behind has 

 been elevated and drained, thus forming a wet iDottom. In 



P 



both wet and di*v bottom 



during summer and 



extends to the natural or artificial levee. AMiere this is the 

 case there ordinarily remains some shrubl:)ery along the base 

 of the levee. Prominent here is usually Equisctum rohuslum. 

 Eragrostis rej)lans covers the banks and its dried stems and 

 leaves arc the most strikin-i: winter feature. 



Islands, 



In 



the sandbars arc enabled to support a vegetation whicli 



from that of the river shore. Con- 



malerially 



Illinois River. 



d Pomdus monilij' 



Cowles* for 

 ongi folia, B( 



vicgacephalus and ,/. tenuis, Cyperus diandrus and C. strigosus, 

 are the plants principally found here. Nasturtium ohtusum 

 and A'', palustre as well as Ambrosia trifida and Chcnopodium 

 amhrosioides anthclminticum are among the first to make their 



appearance. Where the island rises so as to offer a perma- 

 nent foothold (plsiic 11) , S all X longifolla is dominant, forming 

 a dense thicket. Associated with it arc S. cordata X scricca 

 and S. nigra, Betula nigra, Populus monilijcra, Primus sero- 

 tina, Samhucus canadensis and several herbaceous spe(;ies 

 which include, besides those just mentioned, Dcsmodiiim 

 Dillenii and D. paniculatum, Datura Stramonium and D. 

 Tatula, Solanum nigrum., Cyperus aristatus, 0. Schweinitzii 

 and C. spedosus. Plants of Riccia natans are numerous. 



Mudflats. 



The shifting accretions of silt, chiefly on the Illinois side, 

 support, at low water, a vegetation similar to that of the shore 



♦ Cowles, H. C. The Physiograpliic Ecology of Chicago and Vicinity; 

 a Study of the Origin, Development and Classification of Plant Societies. 



Bot. Gaz. 31 : 73. 1901. 



