286 JOHN ERNST WEAVER 



vertically downward course and throw off practically no laterals, 

 except when they enter earthworm holes. Here, strong laterals 

 equaling the main root in diameter, are thrown off and run 

 parallel with it in the hole a foot or two or further. All give rise 

 to abundant root hairs and it is seldom that these roots again 

 enter the soil. The main root may branch very profusely or very 

 little (in hard soil) at the tip. These light-cream-colored roots 

 are very brittle but are easy to follow because of their latex. 

 The acrid taste also is very characteristic and this character was 

 sometimes used to distinguish Hieracium roots, especially near 

 the tip where the latex is less abundant. The longest root 

 reached a depth of 7 feet and 9 inches. Fifteen plants on a 

 northeast slope gave an average depth of 5 feet and 2.8 inches; 

 five on a southwest slope 5 feet and 3.4 inches; and six on a north- 

 west slope 5 feet and 8.8 inches. 



Potentilla blaschkeana 



This very common prairie plant occurs in all situations, but 

 shows a decided preference for the more moist conditions. A 

 few new leaves may appear in the fall, but the plant starts re- 

 newed growth early in April. It blossoms in late May and dries 

 out during July or August, depending upon the environmental 

 conditions. 



The tufted stems are borne on a short, thick crown from which 

 several (2-5) main roots originate. These average about 7 

 millimeters in diameter. They taper off gradually till at about 

 two feet in depth they are often only 2 millimeters in diameter. 

 Here they usually branch dichotomously, and again branching 

 break up into numerous small roots — mere hairs — which have 

 a strong tendency to grow in earthworm holes. These they 

 follow for two feet, perhaps, before entering the soil again. 

 In these holes they give off many threadlike branches which 

 follow down the same hole branching profusely, and often never 

 re-entering the soil. The roots are dark brown in color. They 

 are unbranched or very poorly branched at the tip. Thirty 

 root-systems were examined. Three of the longest roots pene- 



