276 POISONOUS AND MECHANICALLY INJURIOUS PLANTS 



losses of sheep. There is no doubt that it is poisonous, but, 

 because of its tough, fibrous quahty, sheep are not fond of it 

 and will not touch it unless they have no other forage (Fig. 100). 



Fig. q8. — WHITK RHODODENDRON Fig. 99. — CALICOBUSH, OR "MOUN- 



{Rhodndeiuirnn alhijlorum). TAIN LAUREL" (Katmia lalifolia). 



There was once a belief that woody aster caused " grub in the 

 head " in sheep, but it is now known that a fly deposits its eggs 

 on the head of the sheep and the grub {Oestrus ovis) bores in and 

 causes the disease. 



Colorado Rubberweed, or Pingue {Hymenoxys floribunda). — 



Experiments have shown that rubberweed is poisonous to sheep. 

 However, sheep eat the plant only when they are at the point of 

 starvation, and never if they are well fed. The plant has aster- 

 like flowers and grows abundantly in some regions of Arizona, 

 New Mexico, Colorado, and Utah (Fig. loi). 



