56 Forest Club Annual 



twisted and distorted in various ways. The long bristly leaves 

 are arranged in characteristic tufts at the ends of the ultimate 

 branches. Very frequently in the open the branches extend 

 almost to the ground with no clear length of trunk at all. 

 Such trees are scattered here and there among the scattered 

 grasses and yuccas, seldom except in the deeper canyons be- 

 coming sufficiently aggregated to shade out practically all 

 ground cover. In some of the canyons a denser forest aspect 

 prevails. Here the trees are taller with a longer clear length 

 and the crown is shorter and more compact than in the open 

 aspect of the formation. When this maximum density is at- 

 tained all ground cover is excluded except such things as the 

 wintergreens, Pyrola chlorantha and P. secunda and a number 

 of saprophytic species of fungi. The soil becomes richly filled 

 with much organic matter and is deeply overlaid by a layer 

 of pine needles. Even here however the soil is dry. 



Pinus ponder osa is a frequent though not an especially 

 abundant seeder in this locality. Local cone production occurs 

 every year but the frequency of seed years is uncertain. The 

 seeds are often carried down the slopes in a striking manner 

 and one frequently finds a cluster of seedlings on the lower 

 hides of seed-bearing trees standing on steep slopes. In some 

 >f the canyons with scattered stands I found thickets of 

 s-eedlings ranging in height from 3 to 8 feet, so dense as to 

 recall the seeding habit of lodgepole pine. Dense seeding is 

 not typical for Pinus ponderosa, and its unusual reproductive 

 capacity here is rather difficult of explanation from the data 

 that was secured during the past summer. The phenomenon 

 may be due in part to the absence of such great numbers of 

 chipmunks and other seed destroying rodents that are so com- 

 mon farther west. 



At the head of practically every canyon in the region 

 the pine is seen to be slowly invading the grass formation. 

 This invasion is made possible by the exposure of newer and 

 newer rock areas by erosion forces that slowly remove the 

 grassy sod from the uplands. These facts are especially strik- 

 ing at the heads of canyons where the pines follow the out- 

 cropping rocks of the Arikaree series. From these many cen- 

 ters the pine then slowly extends its range farther up the 

 canyon. 



