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THE POPULAR SCIENCE MONTHLY 



however, by the euphonious name of " cortando," or cutting. Had the 

 guayule actually been cut off at the level of the ground, new shoots 

 would have sprung up in many instances to take the place of the re- 

 moved plants. 



Keproductiost of the Shrub 



It has always been fully realized that the limiting factor of the guay- 

 ule industry is the rate of growth and of natural reproduction of the 



" stand," unless the demand for 

 shrub could be met by cultural meth- 

 ods. It is obvious that until the 

 possibilities of culture could have 

 been determined, the proper proced- 

 ure would have been conservation of 

 the mature supply by forestry meth- 

 ods. We may now examine the guay- 

 ule plant from this point of view. 



The guayule is a woody shrub 

 which, in common with most desert 

 plants, is of slow growth under nor- 

 mal conditions. It affects the stony 

 or rocky footslopes and foothills of 

 the limestone hills and mountains 

 within a region of uncertain and at 

 best scanty rainfall. Few and im- 

 perfect records are available for the 

 guayule region proper, but it is 

 safe to say that the total precipita- 

 tion does not exceed 10 or 12 inches. 

 The effective rains fall chiefly in 

 summer. The growth season is there- 

 fore short and the annual increment 

 in growth in length of branches 

 does not exceed an average of 3 to 

 5 cm. (Fig. 12). Plants certainly 50 

 years old do not exceed a meter in 

 height or spread. I have never seen 

 an old plant excelling in both di- 

 mensions. By careful measurements 

 of numerous field plants it has been 

 determined that it takes about 10 

 years for an individual to acquire a 



Fig. 12. The Annual Accretion weight of about 8 ounces, but in the 

 of Growth in a Guayule Twig of /. n ■ « ., .-,-. , 



average rate of growth. following five years it will make 



eight ounces more and will have ar- 



