204 University of California Publications in Botany [Vol. 7 



ant is the irregular belt which skirts the river on both sides from a 

 point about nine miles above Schurz nearly to Wabuska, a distance of 

 eighteen mih-s. This belt will average three-eighths of a mile in width ; 

 the plants are ten to twelve feet apart and have an average weight 

 of about ten pounds. Forest Supervisor W. M. Maule reports about 

 fifty square miles of shrub from Whiskey Flat north to Hawthorne; 

 also about thirty-five square miles between Sweetwater and Fletchers. 

 These areas are in western Mineral County. We have not ourselves 

 visited them and liave not had an opportunity to examine samples. 



The Carson Valley and contiguous areas support about one-hun- 

 dred and fifty square miles of Rabbit-brush of the consimilis form. 

 Several other forms are present, some of them apparently devoid of 

 rubber, but the}^ grow scatteringly around the borders of the main 

 bodies and extend up over the slopes as impurities in the sage-brush. 

 It is on the lower, more nearly level, and alkaline flats of the valley 

 that the best stands of consimilis are found. Here it often grows to 

 the exclusion -of other shrubs, and almost completely covers the ground 

 with plants weighing three to five pounds. 



According to our estimates, District 4 should yield at least 7,680,000 

 pounds of rubber, of which nearly one-half is in or near the Carson 

 Valley. It is probable that further exploration would result in a con- 

 siderable addition to this estimate. 



e. DISTEICT 5— NOETHERN AND CENTRAL NEVADA 



By E. C. McCarty 



This district comprises the counties of Humboldt, Leander, Eureka, 

 Elko, White Pine, and a part of Nye County. In view of the many 

 areas in this section which are favorable to the growth of Chrysotham- 

 nus, it would without doubt prove to be an important one in the pro- 

 duction of an emergency supply of raw rubber. The long valley of 

 the Humboldt River, extending through the counties of Elko, Eureka, 

 Leander, and Humbolt, has many tributary valleys extending both to 

 the north and to the south, and ranging from comparatively short 

 valleys to valleys of more than fifty miles, the Reese River Valley be- 

 ing one of the longer ones. 



The Reese River Valley, which is perhaps typical, is half a mile 

 wide at Caiion, and more than fifteen miles wide at Austin. It extends 

 the entire length of Leander County and into Nye County. Tht' moun- 

 tain range is continuous on either side of the valley and is marked at 



