[From the BuLLeTin oF TME TorREy BoTanicar CLus 47: 441-454. 30 O 1920.] 
Phytogeographical notes on the Rocky Mountain region 
IX. Wooded formations of the Montane Zone of the Southern Rockies 
P. A, RYDBERG 
The Montane or Canadian Zone extends in Central Colorado 
approximately between the altitudes of 2,500 and 3,000 m. In 
the upper part of the zone naturally many of the Subalpine 
plants are common and the lower part has been invaded by those 
‘of the foothills and plains. Many of these plants have been 
omitted in this discussion. As the Montane and Subalpine Zones 
are predominantly wooded, the plant associations are somewhat 
similar. In the open lands or grass-formations they are more 
unlike so far as the composition of the vegetation is concerned, 
the Montane being more like the plains and mesas of the Sub- 
montane Zone, and the Subalpine more like the Alpine Zone. 
The principal forest trees of this zone are the following :— 
bull pine (Pinus scopulorum), lodge-pole pine (P. Murrayana), 
limber pine (P. flexilis), Douglas fir (Pseudotsuga mucronata), 
Engelmann spruce (Picea Engelmannii), Colorado blue spruce 
(P. Parryana), balsam fir (Abies concolor), narrow-leaved cotton- 
wood (Populus angustifolia), balsam poplar (P. balsamifera), 
western black birch (Betula fontinalis), Rocky Mountain alder 
(Alnus tenuifolia), and smooth maple (Acer glabrum). These 
have been discussed in a previous paper.* To these may be added 
several species of willow, hawthorn, and chokecherry, which 
* Bull. Torrey Club 42: 11-25. I5. 
[The BuLLETIN for September (47: 367-440. pl. 15-17) was issued October 19, 
1920.] 
441 
