4 BULLETIN 969, U. S. DEPARTMENT OF AGRICULTURE. 



''it is found along streams." It follows the valley of the Columbia 

 Eiver and its tributaries into Idaho, where it is occasionally found at 

 an altitude of 6,000 feet. It occurs on the Warner Mountains, Modoc 

 County, Calif., at that altitude, but usually in other parts of the 

 United States it is at much lower altitudes. 



Like A. galioides it quite plainly thrives best in newly disturbed 

 soil, but there is no evidence that it is spreading as a weed so rapidly 

 as A. galioides. In comparison with A. galioides it is a larger plant, 

 with wider leaves and flower clusters in a terminal corymb. 



Fit. 1. — Distribtuion of Asclepias mexicana in the United States. 

 EXPERIMENTAL WORK. 



During the summer of 1920, 19 feeding experiments with Asclepias 

 mexicana were made. In all cases sheep were used, the material 

 being fed with the balling gun. In 5 cases the whole top — leaves, 

 stems, and flowers — ^was fed; in 5 other cases leaves and in 9 cases 

 stems were used. The material was obtained through the kindness 

 of Prof. H. M. Hall, of the Carnegie Institution, and was collected 

 at Mount Diablo, Solano, Hollister, and between Newman and Dos 

 Palos, all in California. While dried plant was fed, the dosage is 

 given in terms of green plant for 100 pounds weight of sheep, 75 per 

 cent being allowed for loss in drying. 



In Table 1 the experiments with this plant are summarized. 



