Development of the Vegetation of New York State 79 
OccuRRENCE IN New York: On the summit of Mt. Marey 
above 5000 feet; on Mt. McIntyre and to a less marked de- 
gree on Whiteface and others of the high peaks. 
GENERAL Occurrence; On the higher peaks of New 
England where this aretic element is more strongly repre- 
sented ; in the arctic regions of America (Labrador, Alaska) 
of Greenland and of Europe and Asia and high mountains of 
Southeastern Asia; some of them in the Rocky mountains 
south to Colorado and in Arizona. 
It would seem as if, in this ease, we are dealing with a 
plant population that had no relation to the migration from 
the Appalachian highlands and subsequent establishment of 
species in the region round about, but Harshberger * thinks 
that these species may be relicts of a glacial flora which lay 
along the front of the glacial ice and were the first species 
to migrate northward as the ice receded.* Or according to 
Harshberger if any mountain summits remained above the 
ice sheet (as the nunataks of the Greenland glaciers) such a 
flora might have been conserved there throughout the last ice 
invasion. On the other hand Diels * has shown in his study 
of the Diapensiaceae that certain floristic elements have in 
post-glacial (7) times migrated from the mountain region of 
Southeastern Asia to arctic regions and many mountain sum- 
mit of Asia, Europe and North America. Diapensia lap- 
ponica he regards as in this eategory. This and other boreal 
Diapensiacae are certainly more closely related to the Asiatic 
mountain species than to such “ disjunct ” species as galax 
(Galax aphylla L.) in the mountains of North Carolina or 
pyxie moss (Pyxidanthera barbulata Michx.) of the coastal 
plain sands from New Jersey southward. These two species 
and numerous others of this disrelated or disjunct status, 
must be referred to pre-glacial, perhaps even to the Tertiary 
period. As to the Alpine flora of Mt. Marcy and other iso- 
1 Phytogeographic Survey of North America, pp. 189 and 204. 
2See also Adams, l. ¢., p. 309. 
3 Diels, L. Diapensiaceen Studien. Bot. Jahrb. fiir Syst. Pflanzen- 
gesch. u. Ptlanzengeogr. Band 50: Supplement Band (Engler Fest- 
Band) 1914, pp. 304, 330. 
