Colorado Experiment Station 
plant, and before very much investigative work from the botani- 
cal standpoint had been done. Further investigations have 
shown that Asclepias galioides is probably the species responsible 
for the heavy losses of livestock in Colorado. A. verticillata does 
not occur in large quantities in the State, tho it is present, nor 
is it known definitely at this Station whether or not the two 
species, A. verticillata and A- purnila are toxic. The determination 
of the toxicity of these two species is part of the work planned 
at this station. 
Although the common name ‘'whorled milkweed’' more 
properly belongs to Asclepias verticillata, it has been considered 
advisable to retain the name whorled milkweed, inasmuch as it 
has become so widely used in this State in reference to A. 
galioides. Britton and Brown give the name “bedstraw milk- 
weed” to the ktter? 
Asclepias galioides is a perennial from horizontal, under- 
ground rootstocks. These spread in all directions at distances 
from an inch to a foot underground. These underground root- 
stocks are usually slender, being from 1-16 inch to 1-2 inch in 
diameter, and may grow underground for several feet from the 
main plant. Occasionally taprooted specimens are found, but 
these are the exception. Figures '4 and 5, illustrate the type 
I'Mg-. 4 — The plant has a very effective method of spreading- by creeping hor- 
izontally underground. 
of underground growth. The nature of spreading results in 
characteristic, thick, circular patches. The roots and rootstocks 
may be so thick as to form practically a turf in the upper 
several inches of soil. This turf is very tough and exceedingly 
hard to plow. The seedlings have a single, slender taproot dur- 
ing the first season. 
