THE FOREST COMMUNITY. 



107 



out ill all directions in the surface soil. These send up erect branches 5 inches 

 long, the shorter ones being near the growing tip. As the soil accumulates 

 about the bases of these erect stems, the lower leaves die and only an inch or 

 less of the living tip is exposed. These branches with their dead leaves and 

 accumulated debris occur in such density that they afford a congenial sub- 

 stratum for the abundant rootlets which arise from the horizontal portion 

 especially, as well as from the erect part of the stems. These delicate roots, 

 however, which vary from 1 to 14 inches in length, run off in a horizontal 

 direction in the moist soil just below the mat and seldom reach a depth greater 

 than 3 to 4 inches. They divide into fine, hairlike, well-branched termini and 

 occur in exceedingly great numbers. The main root or roots, depending upon 

 the size of the mat, are tough and somewhat woody, black in color, and from 

 2 to 3 mm. in diameter. They also run off horizontally and usually up the 

 slope, branching profusely and often dichotomously. They spread out some- 

 what fan-shaped and reach a distance of from 3 feet to over 5 feet from the 

 base of the plant. Although they were found to penetrate not deeper than 

 4 to 5 inches, their wide spread and the great numbers and extreme division 

 of their branches enable them to extract sufficient water from the surface soil. 

 Indeed, the termini of many of these branches consists of such a mat of deli- 

 cate, almost microscopic, ultimate branches that it is quite impossible to depict 

 them adequately either with the pen or the camera. 



Fig. 49. — Heuchera parvifolia. 



Fig. 50. — Haplopappus parryi. 



Haplopappus parryi. — This composite forms dense societies in the shady 

 woodland, the rosettes of long leaves almost completely covering the surface 

 over local areas (plate 27, b). It is supplied with a system of stout, much- 

 branched rhizomes that vary in diameter from 2 to 8 mm. and extend from 

 just beneath the surface to a depth of from 6 to 8 inches (fig. 50). From these 

 rhizomes arise large clusters of roots ranging in diameter from 2 mm. to less 

 than 0.5 mm. These roots descend rather vertically or somewhat obliquely 

 and completely fill the soil to a depth of 25 inches, while some reach a maxi- 

 mum depth of 28 inches. The younger roots are supplied with many branches 



