234 GENUS CHRYSOTHAMNUS. 



USES. 



The value of this shrub as a browse plant for animals depends largely upon local con- 

 ditions. Throughout most of its range it is never browsed, except under very unusual 

 circumstances. Toward the north, however, especially in Idaho and neighboring States, 

 the stems and leaves of subspecies speciosus are eaten to a considerable extent by sheep, 

 according to reports from the Forest Service, and even in eastern California this form 

 is sometimes preferred to sagebrush by sheep. In northern regions it furnishes an 

 important winter browse for elk and perhaps also for moose. On the other hand, reliable 

 reports indicate that this species is poisonous to stock under certain conditions, at least 

 in Nevada. If poisonous at all, it is probable that serious results follow only when it 

 is eaten to the exclusion of other foods, or when the animal is in an underfed or weakened 

 condition. 



The possible utilization of Chrysothamnus nauseosus as a supply of rubber has been 

 recently investigated by Hall and Goodspeed (Univ. Calif. Publ. Bot. 7:183-264, 1919). 

 Rubber was found to be present in the cortex and medullary rays in all of the 12 varieties 

 examined, the amount present running as high as 6.57 per cent in individual plants, 

 but averaging only 2.83 per cent even for the best variety. The most constant producers 

 were the varieties inhabiting alkaline soils, especially viridulus, consimiJis, pinifolius, 

 and turhinatus. Field surveys indicated that perhaps 300,000,000 pounds of rubber 

 of good grade are present in the wild shrub of this species in the western United States 

 and that this supply could be drawn upon in case of a national emergency, such as an 

 extensive war during which time overseas importations might be curtailed. The per- 

 centage content of the shrub is much too low to render the extraction of the rubber a 

 profitable undertaking under normal conditions. Even in wartime the total amount 

 obtainable would be insufficient for more than a supplementary supply. It would seem 

 wise, therefore, to carry the investigation of this and other rubber plants still further 

 in the hope of so increasing the yield through breeding, selection, and various other 

 methods of treatment that a permanent rubber-growing industry could be established 

 within the boundaries of the continental United States. 



The herbage of certain subspecies, notably hohleucus and gnaphalodes, is so pleasantly 

 fragrant that the preparation of an essential oil from it would seem to be among the 

 possibilities. 



