564 MANUAL OF POISONOUS PLANTS 



The term loco weed is applied to a great many plants. In addition to the 

 species mentioned above A. oocarpus, A. Crotalaria and A. lentiginosus must 

 be added; species of Oxytropis are considered in another connection. The 

 Sophora sericea of this family, Malvastrum coccineum of the Mallow family 

 and corydalis (Corydalis aurea var. occidentale) have at times been classed as. 

 loco weeds. Thus far none of these plants except those belonging to the 

 pulse family have been found to cause loco poisoning. 



Astragalus Bigelovii Gray. Rattle-box 



A subacaulescent, soft, silky, villous perennial ; long, scape-like peduncles ; 

 flowers in dense spikes ; violet pod oval-oblong, densely woolly, sulcate. 

 Distribution. From S. W. Colorado to Texas and Mexico. 



Astragalus Pattersoni A. Gray 



Perennial, robust, 1-2 feet high, with appressed-pubescence, or sometimes 

 smooth; leaflets oblong, rather thick; peduncles racemosely many-flowered; 

 corolla white, the keel sometimes purplish at the tip; pods smooth, sessile or 

 stipitate ; abruptly contracted within the calyx. 



Distribution. Southwestern Colorado to Utah. 



Astragalus Hornii A. Gray 



A glabrous or minutely pubescent perennial ; slender stems ; leaflets about 

 21, narrowly oblong; peduncles longer than the leaves; flowers in a dense head, 

 or short spike, numerous, small ; calyx teeth subulate ; pods ovate, from a broad 

 base, straight, villous pubescent. 



Distribution. From Southern Utah to California. 



Poisonous properties. It is regarded as a very troublesome weed. Colo- 

 rado has passed a law for its extermination, the state having paid out nearly 

 $200,000 in bounties between 1881 and 1885 to check its ravages. Much has. 

 been written on the subject of the poisonous properties of the woolly loco weed 

 and other members of the genus. Brewer and Watson, in their Botany of Cali- 

 fornia, state that the last species described is said to be poisonous to sheep, and 

 Prof. Chesnut states that stock are affected by this loco weed in the southern 

 part of California. It has certainly been regarded as a poisonous plant for a 

 long time, and numerous investigations have been carried on in regard to its 

 poisonous properties by Dr. Stalker, Prof. Sayre and others ; Dr. Stalker com- 

 ing to the conclusion that the loco poisoning might be brought about through 

 the action of intestinal worms. 



Prof. Sayre reported the death of a jack rabbit with symptoms similar to 

 those recorded for horses and cattle. He was, however, unable to find a 

 poisonous principle. Miss C. M. Watson reported a small amount of an alka- 

 loid from the stemless loco weed, Oxytropis Lainbcrti. Dr. Mary Gage Day in 

 Dr. Vaughn's laboratory found that when a half grown kitten was fed with 

 milk containing a decoction of the root, stem and leaf, emaciation, convulsive 

 excitement, and, finally death occurred; when an adult cat received 60-70 cc. 

 of a more concentrated solution death ocurred on the thirteenth day and sub- 

 cutaneous injection of a concentrated decoction in frogs and chickens caused 

 death in 1-2 hours from heart paralysis. Dr. J. Ott experimented with Astra- 

 galus inollissinius and found that it decreased irritability of the motor nerves; 



