4 BULLETIN 969, TJ. S. DEPARTMENT OF AGRICULTURE. 
"it is found along streams." It follows the valley of the Columbia 
River 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 corvmb. 
Fif. 1. — Distribtuiqn of A sclepias 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 chying. 
In Table 1 the experiments with this plant are summarized. 
