168 Rhodora [Juvl 



ana, P antrum longifolium , etc., all the way and later to the head of 

 the East Branch of the Tuaket where we also found Rhezia virgin ica, 

 Proserpinaca peri in at a and Polygonum robustim. There are Bome 

 beautiful savannahs on the East Branch which, earlier in the season, 

 would repay careful exploration. At the border of one was as hand- 

 some a Polygonum as I ever saw, a slender perennial, obviously a 

 variety of P. hydropiperoides, but extremely tall (1-1.5 in.), with 

 haves almost 2 dm. in length, and with the thick (often 1 em.) pink 

 spikes sessile in mostly digitate fascicles at the tips of the branches. 

 Typical /'. hydropiperoides, which we found common in Yarmouth 

 County, has much shorter leaves and the more slender spikes (com- 

 monly described as "filiform") scattered along the flowering branches. 

 This was the end of the collecting but only the beginning of the 

 more exacting and unending task of accurately working out the 

 results 17,000 sheets of carefully prepared specimens representing 

 3,600 numbers, nearly every isolated species to be intensively studied, 

 lest, like the Lophiola, avc should superficially place it with the wrong 

 species. And, although the detailed results cannot yet be fully 

 stated, it is now safe to say that, of the indigenous vascular flora of 

 silicious southwestern Nova Scotia, approximately ISO out of the 800 

 known species are cither isolated from the more continuous coastal 

 plain flora of the South or are endemic derivatives from it, while 

 such a typical coastal plain genus as Bartonia seems in Nova Scotia 

 to be more highly developed than on the coastal plain itself. Fur- 

 ther exploration will greatly increase the proportion of isolated coastal 

 plain types, for we have glimpsed scarcely 1% of the silicious area 

 and most of the significant plants are highly localized and found 

 where least expected. But if there wen- need of further evidence 

 that, since the Pleistocene glaciation the continental shelf of eastern 

 North America has been high in the air, affording, an essentially 

 continuous line of migration across the mouth of the Gulf of Maine 

 to Nova Scotia, thence to Newfoundland, that evidence is now 

 abundantly at hand. A striking feature of this migration northward 

 of the southern coastal plain flora is the fact, that several distinctive 

 species or genera, ScMzaea pusilla (fig. 11), Lophiola (fig. 17), Ilub- 

 enaria flam, and perhaps Ceratiola, reached Nova Scotia without 

 establishing colonies on Long Island, Cape Cod or Nantucket. This 

 M Ould seem to indicate that the uplifted shelf was a region of some 



