480 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



at the mouth of Mackenzie River (Lat. 69°), but it swings south- 

 ward going east, so that it meets the Hudson Bay about 10° 

 further south. On the Labrador Peninsula the most northern 

 point is also about Lat. 59°. The flora consists mostly of low 

 perennial herbs and a few depressed shrubs. There is no distinct 

 shrub-belt as in the Alps or the Scandinavian Mountains. I have 

 already discussed the composition, distribution, and origin of its 

 flora in three articles published in the Bulletin of the Torrey 

 Botanical Club. 



IL SuBALPiNE Zone 



This is practically the same as Dr. Merriam's Hudsonian Zone 

 and corresponds to the true Hudsonian Zone of the East, to the 

 dwarf birch region of the Scandinavian Mountains or the sub- 

 alpine regions of Switzerland with Pinus montana, Alnus viridis, 

 and species of Rhododendron. It resembles most that of the 

 eastern Hudsonian, as the forest consists of spruces, balsams, 

 larches, and aspens, but of these the only species in common is 

 Populus tremuloides. The characteristic trees of the eastern 

 Hudsonian are Picea canadensis and P. Mariana, Abies balsamif era, 

 and Larix laricina; those of the Subalpine Zone of the Rockies are 

 Picea Engelmanni, Abies lasiocarpa, and Larix Lyallii, the last 

 only in the Northern Rockies. These three trees are also found 

 in the Cascades, i. e., the northern part of the Pacific highlands. 

 On the more exposed and drier ridges, especially on the southern 

 side of the mountains, two pines are found, viz. Pinus albicaiiUs 

 in the Northern and P. aristata in the Southern Rockies, but 

 neither is of any great importance. 



Merriam^ in his life zones of Idaho distinguishes between a 

 Subalpine or Timberline Zone and a Hudsonian or Spruce Zone; 

 the former being the region between the upper and lower timber 

 lines. Such a zone can not be upheld from a botanical viewpoint 

 and evidently Dr. Merriam has given up the idea. The open 

 grass-covered areas of this region are essentially Alpine-arctic, 

 while the wooded spots belong to the Subalpine or so-called 

 Hudsonian Zone. Mr. Vernon Bailey, ^ who follows Merriam 

 very closely, in his Life Zones and Crop Zones of New IMexico secMiis 

 to ha\e limited the Hudsonian Zone nearly to what Merriam at 



' North American Fauna 5: 22. 1891. 

 ^ North AmericanFauna 35: 11. 1913. 



