2 BULLETIN 942, TJ. S. DEPARTMENT OF AGRICULTURE. 



branching, are 3 to 12 inches high, tufted, and puberulent. The 

 main root is horizontal, branching-, and produces adventitious buds. 

 Figure 2 of Plate I shows plants growing from adventitious buds 

 on the root. The leaves, which are 1 to 2 inches long, are sessile, nu- 

 merous, crowded, and irregularly alternate to verticillate, linear- 

 foliform, revolute, and scabrous-puberulent. The flowers are in 

 terminal branching umbels, few to many flowered, with short pedun- 

 cles, and are scabrous-puberulent. The greenish-white corolla has 

 oblong lobes and white oblong hoods, which are hastate-sagittate in 

 back view and shorter than the horn. The follicles are erect, puberu- 

 lent and H to 3 inches long. The plant is found in adobe draws, in 



Fig. 1. — Distribution of Asclepias pumila. 



dry plains, and in foothills from southeastern Montana and south- 

 western North Dakota to the Texas Panhandle and central New 

 Mexico. It is most abundant on the plains of Colorado. 



Text figure 1 shows the distribution of the plant. Although it has 

 a root system and seeds similar to Asclepias galioides, it has not 

 spread widely. It usually is scattered in small patches in draws. 



The systematic position of Asclepias pumila is discussed in United 

 States Department of Agriculture Bulletin 800, pages 5 and 6. 



EXPERIMENTAL WORK WITH A. PUMILA. 



All experimental work which was carried on in the summer of 

 1919 was with sheep, and the material in all cases was administered 

 by the balling gun. 



