110 American Fern Journal 



forming here and there deep, dark green pools, and 

 finally reaching the valley of the Chama River, where 

 it becomes slower and shallow. For most of its course 

 it traverses a high plateau, through which it has cut a 

 deep, narrow gorge, in some places not more than a 

 hundred yards wide, bounded by vertical cliffs from two 

 to three thousand feet high. Viewed from a short dis- 

 tance the cliffs appear nearly bare of vegetation, aside 

 from the scattered spruces that have gained a precarious 

 footing in earth-filled crevices, but a closer inspection 

 shows them covered with small lichens, whose colors 

 take on intenser hues in wet weather and produce a 

 conspicuous change in the coloration of the rocks. 

 Narrow crevices in these rocks are a favorite habitat 

 of several ferns. The summits of the cliffs and their 

 basal slopes, where the canyon widens, support a heavy 

 plant growth which can be readily divided into two 

 life zones. The "box" of the canyon proper, the higher 

 slopes of the mountains, as well as their northern slopes 

 at lower levels, and the banks of the streams, are densely 

 covered with vegetation characteristic of the Canadian 



Zone. 



Mountain 



a 



ana), Douglas spruce (Pseudotsuga mucronata), white 

 fir (Abies concolor), and aspen (Populus aurea). The 

 plant life of the lower slopes and of the great rock slides 

 at the base of the cliffs is typical of the Transition Zone. 

 The only tree is the Rocky Mountain yellow pine (Pin us 

 brachy ptera) , except along the streams, whose banks are 

 fringed with the mountain cottonwood (Populus angusti- 

 folia). Beneath the pines there is usually a thick shrubby 

 undergrowth, composed chiefly of deciduous scrub-oaks. 



with a preponderance locally of choke-cherry (Padua 



melanocarpo) and service-berry (Amehmchier sp.)- 



In this restricted region the writer collected the twelve 



species of ferns and fern allies which are enumerated 

 below. 



