68 



MANUAL OF POISONOUS PLANTS 



Fig. 17. A. Fruit of the Cocklebur (Xanthium canadense), causes mechanical in- 

 juries to hogs when eaten by them. B. Sandbur (Cenchrus tribuloides). C. Burdock 

 (Arctium major). D. Boot Jack (Bidens frondosa). E. One of the Borages (Cynoglossum). 

 F. Carrot (Daucus Carota). 



branches of Greasewood (Sarcobatus vermiculatus) easily penetrate the skin 

 and sometimes induce pus infection. The bristles and spines of the rose and 

 stiff bracts of the Russian Thistle may be the cause of injury to animals and 

 men. The small, barbed trichomes of the calyx of Crimson Clover (Tri folium 

 incarnatutn}, according to Prof. Coville, produce phytobezoars similar to those 

 commonly produced by hair. Dr. Trelease has described similar bezoars from 

 the barbed trichomes and spines of cacti. Millet and barley awns are known 

 to produce similar balls in horses as well as in cattle. Corn stalks, when eaten 

 with an insufficient amount of water, produce impaction. This has, however, 

 been attributed to other causes also. Bloat is known to follow the use of such 

 forage as white and red clover, alfalfa, pigweed and many other plants con- 

 sumed under the same conditions. 



