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M. L. FERNALD 
Hills and the Saskatchewan Plains to Oregon and California, reap- 
pearing in northern Asia, and on Anticosti Island at the mouth of the 
St. Lawrence. A very similar distribution is shown by the Section 
Conyzopsis of the genus Aster, a unique group of annual essentially 
rayless plants with three species: the widely dispersed A. angustus of 
the Great Plains of western North America, salt plains of southern 
Siberia and Afghanistan and shores of the lower St. Lawrence; a second 
species, A. frondosus, of alkaline spots from the Rocky Mountains to 
the Pacific; and a third species. A, latirentianus , known only from 
saline or brackish sands of the Gulf of St. Lawrence. A very similar 
range is shown by several aquatic plants of which a good illustration 
is Potamogeton filiformis, var. Macounii (fig. 7), widely spread from 
the southwest side of Hudson Bay to Alberta and southern California, 
but eastward known only from Prince Edward Island and the Mag- 
dalen Islands, where it is a highly characteristic plant. In fact, just 
as recent botanizing on Cape Cod and Nantucket is taking much of 
the distinctive lustre from the botanical fame of the New Jersey Pine- 
barrens, so the exploration of the saline sands of the lower St. Law- 
rence, Prince Edward Island and the Magdalen Islands is gradually 
adding to our known flora of the Northeast a large proportion of the 
plants of the wet areas of the Great Plains and saline prairies. 
So much, very briefly, for the temperate American affinities of the 
New England-Maritime Province-Newfoundland flora. Now turning 
to the boreal affinities, we have, of course, an extensive Hudsonian 
flora, already mentioned, which extends almost uninterruptedly from 
the Barren Lands and the Labrador Peninsula to northern New 
England; but in case of the boreal as with the temperate floras the 
greatest phytogeographic interest attaches to the species of discon- 
tinuous range. The most familiar examples of discontinuous ranges 
in our arctic-alpine flora are, naturally, the widely dispersed circum- 
polar types, such as Saxifraga oppositifolia, of broad range across 
Arctic Europe, Asia and America, extending locally southward to 
favorable alpine or subalpine habitats, in America the limestones of 
w^estern Newfoundland, Anticosti, Gaspe and the northern Green 
Mountains in the East, the northern Rocky Mountains in the West; 
or Salix reticulata of similar occurrence in the Arctic, but in America 
extending southward very locally only to western Newfoundland, 
James Bay, and southern Alaska. Of much more restricted range in 
the North are the Greenland-Labrador types, many of which, like 
