358 MIXXESOTA BOTANICAL STUDIES. 



The plants which form large trees on the islands are : 



Ace?' saccharimim, Populus dcltotdcs, 



Betula nigra, ^ie7'ais platanoides, 



Fraxinus lanceolata, Salix amygdala ides, 



Fraximis 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.) 



Cephalanthus occidentalis, Salix Jluviatilis, 



Cornus amonwn, Salix nigra. 



Three species of woody vines are common throughout the 

 islands. The Virginia creeper, Parthenocissiis quinquefolia, 

 and wild grape, Vitis viilpina, 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 iamariscina, Miimilus ringens, 



Apocynuin cannabinum, Onoclea sensibilis, 



AriscRma dracontium, Polygomini hartzvrightii, 



Bidens co7nosa, Polygormm hydropipcr aides , 



Bidens frondosa, Polygonjim incarnatum, 



Btdens Icsvis, Polygonum ptmctatum, 



Cicuta hulbifera, Polygontim virginianuyn, 



Heleniuvi atiiumnalc, Physalis -philadelphica, 



Ilysanthes gratioloides, Physostegia virginiana, 



Lipfia lanceolata. Ranunculus pcnnsylvaniciis. 



Lobelia cardinalis, Scutellaria lateriflora, 



Lycopus americanus, Stachys palustris, 



Lycopus Incidus, Steironema ciliata, 



Lycopiis rubellus, Teucrium canadense, 



Lycopus virginic7is, Urtica gracilis, 



Ly thrum alatum, Urticastrum divaricatum. 

 Mentha canadensis. 



