221 



zone of Iris occurs on each side of the Avillows. AVlierever Rosa occurs 

 Spirea abounds. Spirea tonieutosa on the east side and Spirea salicifolia 

 on the south side. Along tlie damper parts of this area grow Polygonum 

 sagittatum, P. parvifolium, P. hydropiperoides, Epilobum strictum, Plant- 

 ago pusilla, Galium tritida, Panthorum sedoides, and Alisma plantago. 

 There is a fine carpet of false purslane (Ludwigia palustris) over the entire 

 area. 



The ditch iiself contains water only in times of flood. Notwithstand- 

 ing this it is almost covered with floating forms of liverworts (Riccia 

 fiuitans, Ricciocarpus natans). Yellow wated lilies (Nuphur advena) 

 grow in it for more than half its length. 



At the west end, there is a sort of bay that has recently been fairly 

 well drained. This has resulted in the introduction of a great variety 

 of species. Most of those found further east along this side persist. 

 In addition occur: Eupatorium perfoliatum, purpureum, Helianthus an- 

 uuus, Solidago Canadensis, Bidens chrysantheuroides, Pj^cnantheum lan- 

 ceolatum, Mentha Canadensis, Lycopus sinuatus. Yirginicus, Potentilla 

 argentea, P. parviflora, and Verbena hastata. It is a tine example of con- 

 fusion of species during a change of conditions. 



The East Slope (Fig. 10). — On the east side there is a row of willows 

 near the margin. Inside this there is a broad zone of roses (Rosa Caro- 

 lina), in which is mingled poplars (Populus tremuloides), swamp oaks 

 (Quercus tinctoria). and elms (ITmus Americana). 



General Remarks and Conclusions. 



First. — On account of the great depth of the peat and the slope of 

 the underlying sand Ave may conclude that this swamp was a lake which 

 has been filled with vegetation, and that the process still continues. 



Second. — That in recent years the groAvth has been most rapid in the 

 center of the swamp, thus elevating it and forcing the drainage lines to 

 the margins. This was made possible through the inhibition of the proc- 

 esses of decay so often noted in sphagnum SAvamps. 



Third. — The fact, that there are no peaty remains on the level plain 

 surroimding the present SAvamp, indicates that the first lake was a veiy 

 ephemeral one. When a topographic form exists for a short time its 

 effect upon the tlora is so slight that an interruption may be caused in the 

 usual succession of plant life. An excellent illustration of this fact has 

 been obserA'cd in connection Avith these studies in the case of Little Eagle 



