24 VEGETATION IN COLORADO-HOLM. [MEM0IRS [voTxTx; 



Trifolium, section Lupinaster Moench. 



In the Rocky Mountains this section is represented by the Alpine T. nanum Torr.. T. Parryi 

 Gray, and T. dasyphyllum T. et Gr.; in the European Alps by T. alpinum L.; in Siberia by 

 T. eximium Steph., and T. Lupinaster L. ; in the Caucasus by T. polyphyllum C. A. Mey. Thus in 

 the mountains of these countries the section has developed, exemplified by very distinct species, 

 none of which have become distributed beyond their natural boundaries, and none having ever 

 been recorded from the high northern latitudes; in other words, we have before us the develop- 

 ment of a very natural section at very remote stations, but all Alpine. 



Dryas octopetala L. 



We have seen from the table (p. 13) the enormous geographical range of this plant, being 

 not only circumpolar but occurring in the vast mountain ranges farther south, but absent from 

 the Himalayas, where Sieversia elata Royle is the nearest ally. 



Three species are known of the genus, D. octopetala L., D. integrifolia Vahl, and D. Drum- 

 mondii Hook. On this continent D. octopetala L. abounds in the Rocky Mountains, and has 

 been reported from several stations in Alaska; it was said by Pursh to have been found on the 

 White Mountains (New Hampshire) about a hundred years ago, but has never been found there 

 since. In Greenland D. octopetala L. is very rare on the western coast, but is not infrequent 

 on the eastern, between latitude 73° and 76° N. 



D. integrifolia Vahl, on the other hand, is very frequent in west Greenland from latitude 

 60° to 76° 7' N. On this continent the species is distributed from Labrador to Bering Straits, 

 occurring in the Rocky Mountains of Canada, where Moose Mountain, Elbow River, is the most 

 southern station of this plant. From Alaska the distribution extends to eastern Siberia " terra 

 Tschuktschorum ad sinum St. Laurentii, inque insula St. Lauren tii" (Ledebour, 1. c). 



With regard to the third species, D. Drummondii Hook., this is also a native of the Rocky 

 Mountains of Canada and extends as far north as the Arctic shores. It has been reported from 

 the island of Anticosti, where D. integrifolia Vahl also grows. In eastern Siberia the species is 

 reported from Aldan River. 



While Dryas octopetala L. undoubtedly developed in the polar mountains, the center of 



the two other species is evidently to be sought in the Rocky Mountains and in the most northern 



part of these. Similar to D. octopetala L., D. integrifolia Vahl inhabits dry and rocky places, 



while D. Drummondii Hook, never grows on the mountain slopes, but prefers gravelly beaches 



and bars of rivers. Macoun (1. c, p. 515) states that this species is abundant in the gravel at 



the mouths of mountain streams from Morley through the Rocky Mountains to Donald, in the 



Columbia Valley. 



Sieversia Rossii R. Br. 



The species was founded upon specimens from Melville Island. 23 Since then the plant has 

 been reported from northeastern Siberia and from Alaska. By a number of collectors the 

 plant has been found in the Rocky Mountains from Wyoming to Arizona and described as a 

 new species of Geum, of Sieversia, and of Acomastylis, 24 "turhinata." Being in possession of a 

 copious material which I collected in Colorado, I have carefully compared these specimens 

 with the Arctic, and I am unable to detect any character of specific importance. The plant in 

 Colorado naturally varies somewhat in accordance with altitude, and the specimens from the 

 high Alpine regions are in all respects identical with the Arctic. Some few other species are 

 known from Alaska, viz, S. dilatata R. Br., and S. glacialis R. Br., while S. triflora R. Br. shows 

 a far wider distribution from Labrador to British Columbia, south to New York and Mexico. 

 Another North American species is S. PecJcii R. Br., a native of the mountains of New Hamp- 

 shire and North Carolina. In the Alps of Switzerland and Germany S. reptans Spreng. and 

 S. montana Willd. inhabit the Alpine slopes, and, as already mentioned, there is also a species 

 in the Himalayas, S. elata Royle. Of these S. glacialis R. Br. and S. Rossii R. Br. are the only 



n Brown, Robert: Chloris Melvilliana (Suppl. Appendix Parry's Voyage). London, 1823. 

 « Greene, E. L.: Leaflets, vol. 1, p. 174. 



