INTRODUCTION. 23 



southeastern coasts of Mt. Desert, — an opportunity, how- 

 ever, which would readily be presented on the low shores, 

 and in the coast marshes and lagoons of the Cranberry 

 Isles. Yet it would seem improbable that all these plants 

 reached the Cranberry Isles only. Montia has been found 

 also on the Duck Islands, and might likewise, and as 

 readily, be carried by ocean currents farther on, at least to 

 the westward adjoining shores of Mt. Desert. There in 

 the southwestern part of the Island similar conditions 

 existed for the colonization of these plants as on the Cran- 

 berry Isles, yet in fact they do not appear, so far as known. 

 If, on the other hand, they came from the south, remain- 

 ing behind in the progress of plant life northward after 

 the glacial period, and finding here favorable surroundings 

 for their existence, all the more we should expect to find 

 these plants also in the southwestern projection of Mt. 

 Desert Island. Here the land would be reached earlier 

 in the northward march, and would be found to present 

 the same conditions of soil and of general physical char- 

 acter as the Cranberry Isles. As, however, none of these 

 peculiar plants except Symploearpus and Hippuris appear 

 even on this part of Mt. Desert, the evidence at present 

 seems in favor of a later migration from the north, rather 

 than of the much earlier introduction from the south. 

 The whole subject is one of great interest, and will repay 

 careful study. 



Another interesting feature of the Mt. Desert flora is 

 shown by the comparatively small representation of in- 

 troduced foreign plants, especially of weeds of cultivated 

 ground. Excluding garden escapes and a few plants 

 naturalized by intentional introduction, we find that the 

 number of weeds is very small in comparison with that 

 of similar areas in New England. The reason is a very 



