LEGUMINOSAE— ASTRAGALUS 567 



Arizona and New Mexico there occur other leguminous plants which are known 

 as loco weeds. Some of these are poisonous and the symptoms of locoed ani- 

 mals and the pathological findings are similar to those produced by the plants 

 found in the eastern Rockies, especially in Colorado, where the purple loco is 

 abundant. Dr. Crawford finds barium in them which he thinks may be connected 

 with the poisonous effects of the plants. In California the A. diphysus, A. ari- 

 conicus, A. Thurberi and A. Bigelovii are called "rattleweeds" and have been 

 suspected. They are being studied by Dr. Crawford of the Bureau of Plant 

 Industry. 



In his most recent paper on Loco Poisoning * Dr. Marsh affirms Dr. Craw- 

 ford's opinion that the purple loco weed {Astragalus mollisimus) is more poison- 

 ous than the white species (Oxytropis Lamherti). Dr. Marsh adds this caution, 

 that since such animals are extremely sensitive to strychnin, it has been found 

 necessary to give it in small doses. He says : 



The daily doses should not ordinarily exceed three-twentieths or four-twentieths of a 

 grain, or 0.009 to 0.012 of a gram. Large animals may take as much as one-half grain, 

 but this is a maximum dose and often will be found too much. It was also found that 

 sodium cacodylate when given to cattle in hypodermic injections of 6 grains, or 0.4 grains, 

 daily, commonly gave beneficial results. The best results, however, w«re obtained from the 

 use of strychnin and Fowler's solution as already outlined. 



It may be added, in regard to the question of immunity, that loco poisoning comes 

 on in a slow and cumulative manner so that there is no possibility of animals becoming 

 immune. 



It does not seem that the above is final in regard to all of the loco weeds. 

 It is hardly likely that Profs. Power, Sayre, Gambler, and others have been 

 entirely wrong in regard to their conclusions. When we find that related plants 

 have strongly toxic properties we may expect to find the same properties also 

 in some of these plants. 



17. Oxytropis DC. Stemless Loco Weed 



Perennial herbs or sometimes shrubby, generally acaulescent, with numerous 

 tufts of short stems covered with scaly stipules. Flowers in racemes or spikes; 

 calyx teeth nearly equal; petals clawed; standard, erect, keel erect; stamens ap- 

 pendaged ; diadelphous ; pod more or less 2-ceIled or 1-celled sessile or stalked. 

 About 125 species of the North Temperate regions. Most of our species are 

 western. Several of our species are known to be poisonous to live 

 stock. The following species of this genus are classed with the loco weeds : 

 O. Lamberti, O. deflexa and O. multiflorus. According to Greshoff the young 

 leaf of Oxytropis lapponica has an extremely bitter taste; there is also an indi- 

 cation of saponin. On analysis the leaf was found to contain hydrocyanic acid. 

 Greshoff also found hydrocyanic acid in the seeds of O. sulphiirea. 



Oxytropis Lamberti Pursh. Purple or Stemless Loco Weed 



Nearly acaulescent perennial herbs or shrubby plants, with tufts of very 

 numerous short stems coming from a hard and thick rootstock containing many 

 scaly stipules; stems and leaves are covered with silky and fine appressed hairs, 

 or smooth; leaves pinnate; leaflets linear; flowers racemose or spicate, rather 

 large and elongated, purple, violet, or sometimes white; stamens diadelphous; 

 keel tipped with a sharp projecting point. 



•Farmers Bull. U. S. Dept. Agr. 380:16. 



