30 
BULLETIN 1245, U. S. DEPARTMENT OF AGRICULTURE. 
of from 4,000 to 7,600 feet, but are more commonly found between 
5,000 and 6,000 feet. 
There is good reason for thinking that this plant is responsible 
for many losses of cattle from October to midwinter, at a time when 
other forage is scarce. Experimental work has shown definitely that 
it is poisonous to sheep, the toxic dose being about 1 pound for 
a 100-pound sheep. Care should be taken that stock, especially 
when poorly nourished, should not graze to any extent upon this 
plant. 
From what is known of B. pteronioidcs, it seems that it would not 
be difficult to remove it from a range, as it is local in distribution 
and easily destroyed by a mattock. 
«aiii" r i m 
sg*r v vfp^" 
fla^.wnk 
WOODY ASTER (Xyloivhiza parreyi). 
The woody aster (Xylorrhiza parreyi), shown in Plate XL, occurs 
in great abundance in certain regions in Wyoming, and has been 
accused of causing losses of sheep in those localities. There appears 
to be no doubt that the 
plant is poisonous. It 
is a fibrous plant, how- 
ever, and is very dis- 
tasteful to sheep un- 
der ordinary circum- 
stances, so there is very 
little danger from it, 
provided the sheep are 
kept in a region where 
sufficient feed is ob- 
tainable. 
COLORADO RUBBER PLANT, 
OR PIXGUE (Hymenoxys 
floribunda). 
The Colorado rubber 
plant, or pingue {Hy- 
menoxys floribunda)) 
shown in Plate XLI, 
is confined to the northern part of New Mexico and the southern 
part of Colorado and Utah, and in certain localities grows in very 
great abundance. Its asterlike flowers are quite conspicuous, and 
the plant is readily distinguished from other similar plants be- 
cause of the dark golden-yellow color of the flowers. The rubber 
planl has had a good deal of advertising because it contains a 
certain amount of rubber and has been the subject of commercial 
exploitation. It is claimed, especially in southern Colorado and 
northern New Mexico, that sheep feeding on this plant late in the 
winter suffer severely. 
Experimental work has proved that the plant is poisonous to 
sheep, but it has been found difficult, under corral conditions, to 
make them eat it. Field observations have shown that in the lo- 
calities where animals are reported to have suffered, the sheep in the 
latter part of the winter are frequently kept under conditions closely 
approaching starvation, and at such times doubtless, by force of 
circumstances, they eat more of the plant. It is doubtful whether 
there would be any loss from this plant if bands were properly fed. 
Fig. 20. — A sheep poisoned by rayless 
com a wrightii). 
?oldenrod (Iso- 
