282 JOHN ERNST WEAVER 



the root as a whole a beaded appearance. In general the roots 

 are very poorly branched. Ten plants on a northwest slope 

 gave an average depth of 3 feet and 11.3 inches, while five on a 

 northeast slope reached an average depth of 4 feet and 6.7 inches, 

 thus giving a total average root depth of 4 feet and 0.7 inch. 



Helianthella douglasii {Fig. 15) 



This and the following composite are both important and 

 abundant prairie species. They occur typically on dry hill- 

 sides, often as many as 2-8 per square meter. While Helian- 

 thella adds much to the estival prairie aspect, with its large yellow 

 flowers, its blossoming period is well past when Hoorebekia 

 racemosa comes into bloom in late July. The latter is one of the 

 few species giving tone to a poorly defined autumnal aspect. 



Helianthella has a tap root with a diameter seldom more than 

 0.8 inch. It throws out many big laterals just beneath the sur- 

 face, most of which come off within the first 18 inches of soil, 

 although there are some lower, and a cone may be formed all the 

 way to the tip. The laterals usually pursue rather a vertically 

 downward course, and are profusely branched. Helianthella 

 branches more at the tip than does Hoorebekia, and it also throws 

 out more laterals than that species. The roots are reddish- 

 brown in color, those of Hoorebekia are white. They have a 

 strong, characteristic odor, and an oily taste slightly resembling 

 carrots. By these characters it is easy to distinguish Helian- 

 thella roots from others. Twenty plants were examined. An 

 average depth of 4 feet and 4.5 inches was found; the deepest- 

 rooted plant exceeding this by only 12.5 inches. Six plants 

 on a southwest slope gave an average root depth of 4 feet and 

 4 inches; five on a northeast slope 4 feet and 8.6 inches; and ten 

 on a northwest slope 4 feet and 7.1 inches. 



Hoorebekia (Aplopappus) racemosa (Fig. 16) 



Thirty-four plants were examined. The deepest roots reached 

 7 feet and 7 inches, and 11 feet respectively, but the average 

 depth was 5 feet and 5 inches , Hoorebekia has a strong tap root 



