358 MINNESOTA BOTANICAL STUDIES. 



The plants which form large trees on the islands are : 



Acer sacchartnum, Populus deltoides, 



Betula nigra, Qitcrcus platanoides, 



Fraxinus lanceolata, Salix amygdala ides, 



Fraxinus nigra, Ulmus americana. 

 Gleditsia triacanthos, 



The following species do not attain large size, but are either 

 scattered throughout as shrubs or small trees, or form a dense 

 low growth on some of the lower grounds of the mud flat. 

 (Plate XXV., A.) 



Cephalantkus occidentalism Salix Jluviatilis, 

 Cornus amonum, Salix nigra. 



Three species of woody vines are common throughout the 

 islands. The Virginia creeper, Parthenocissus quinquefolia, 

 and wild grape, Vitis vulpina, are abundant, covering and in 

 many cases killing large trees. The climbing poison ivy, Rhus 

 radicans, is common throughout the most densely wooded parts. 

 It sometimes climbs to a height of twenty-five or thirty feet, and 

 develops a stem from two to three inches in diameter. 



During the late summer and autumn the mud-flat throughout 

 is covered with a dense growth of coarse herbs most of which 

 are perennials. 



The following herbaceous plants grow on the mud-flat. 



Acnida tamariscina, Mimulus ringens, 



Apocynum cannabinum, Onoclea sensibilis, 



Ariscema dracontium, Polygonum hartivrightii, 



Bidens comosa, Polygonum hydropiper aides, 



Bidens f rondo sa, Polygonum incarnatum, 



Bidens Icevis, Polygonum punctatum^ 



Cicuta bulbifera, Polygonum virginianum, 



Helenium aulumnale, Phy salts philadelphica,, 



Ilysanthes gratioloides, Physostegia virginiana, 



Lippia lanceolata, Ranunculus pennsylvanicus , 



Lobelia cardinalis, Scutellaria lateriflora, 



Lycopus americanus, Stachys palustris, 



Lycopus hicidus, Steironema ciliata, 



Lycopus rubellus, Teucrium canadense, 



Lycopus virginicus, Urtica gracilis, 



Ly thrum alatuni, Urticastrum divaricatum. 

 Mentha canadensis, 



