Feb. 1908.] 



107 



Saps and Exudations- 



"The supply of the Guayule is very 

 unevenly distributed in the territory the 

 plant occupies. In most places the 

 plants are isolated, growing sometimes 

 in large an often in small numbers 

 among the other plants. At rare 

 intervals small patches are found where 

 it is predominating in the chaparral 

 flora. It is very difficult to make an 

 estimate of the average supply per 

 hectare, both on account of the uneven 

 distribution of the plant and because of 

 the difference in size of individual speci- 

 mens. In favourable territory I have on 

 several occasions counted thirty to 

 forty plants on an area of 100 square 

 meters, which would mean a total 

 supply of 3,000 to 4,000 Guayule plants 

 per hectare (=1,215 per acre). The 

 differences between the size and the 

 weight are so great that in places where 

 the plants are small and grow close 

 together ten plants have a weight of 

 only one kilogram (=25 lbs ), while in the 

 best territories some of the trees weigh 

 as much as 3 kilograms each. The 

 average weight will probably not exceed 

 500 grams (1A lb.) per plant. Estimates 

 of the Guayule supply in large areas vary 

 from 500 to 800 kilograms per hectare, but 

 the distance between the different places 

 where the plants are found is often con- 

 siderable, and must be taken into con- 

 sideration. The Guayule shrub is about 

 two feet high, with knotted spreading 

 branches and sparse, greyish leaves. 

 The whole plant contains rubber, with 

 the exception of shoots bearing leaves 

 and flowers. Consequently the whole 

 plant is gathered and the supply is 

 rapidly exhausted on the area where 

 gathering is done. Even the roots are in 

 most cases pulled up by the collector, 

 and the opportunity for re-growth is 

 reduced to a minimum. The rate of 

 growth is very slow, so that a plant 20 

 inches high is three to four years old, 

 while plants five years old are not more 

 than 30 inches high. Such a plant would 

 weigh about four pounds. In view of 

 these facts it seems more than illusiouary 

 to speak of growing the Guayule plant 

 for commer cial purposes. Brought under 

 domestication the plant could naturally 

 be made to grow much faster, but there 

 are still other factors to be taken into 

 consideration. The dry country in 

 which the Guayule plant grows has a 

 very scanty and irregular rainfall. For 

 an agricultural crop that kind of land 

 can hardly be expected to supply the 

 necessary requirements, and the un- 

 certainty about the germination of the 

 seed brings in such anelemeutive chance, 

 that indeed very much faith in Provi- 

 dence must be present to undertake the 

 growing of Guayule without any pro 

 vision for occasional artificial irrigation 



The price paid has been as high as $43 

 per ton of dry plants, pressed into bales, 

 and delivered at railroad station. With 

 that price, and the slow growth of the 

 plant, it is difficult to see how any one 

 can in earnest consider the cultivation 

 of Guayule. Factories operating a large 

 area should naturally take some steps 

 for re-covering the ground with Guayule, 

 but beyond sowing the seeds and taking 

 the chance of their germinating and 

 growing in a few years to a size that 

 can be utilized, it is hardly possible to do 

 anything. As for the fear of Guayule 

 filling the market to the exclusion of 

 crude rubber from previous sources of 

 wild tropical rubber and from present 

 and future plantations, such an idea is 

 hardly worth refuting. If we remember 

 that the requirements at present of the 

 United States alone amount to more 



than 60,000,000 lbs. annually, a 



simple mathematical calculation, based 

 on the most exaggerated expectations of 

 the output of Guayule rubber from the 

 entire territory where it is growing, will 

 show the role this product could have in 

 the world's market, even supposing that 

 the supply was inexhaustible and as 

 large as claimed by Guayule enthusiasts. 

 It may be added that the quality of 

 Guayule rubber is very inferior, the 

 rubber being very sticky and rapidly 

 deteroriating. The market value is very 

 low in comparison with that of first-class 

 rubbers, but it still leaves a wide margin 

 for profit, and the supply of rubber 

 plants is apparently enough for a few 

 factories, not too closely situated. As 

 a special product the Guayule has a 

 market of its own, and if cultivation of 

 this plant can be accompolished on a 

 profitable basis, it will prove a great 

 boon to the sterile parts of Northern 

 Mexico. Another rubber plant of Mexico, 

 Euphorbia elastica, has been spoken of. 

 I have seen the plant, but have not been 

 able to obtain a sample of the product, 

 which I understand, however, somewhat 

 resembles the Guayule rubber. In addi- 

 tion to this article, another communi- 

 cation on the same subject by Dr. 

 R. Eudlich appeared in Der Tropen- 

 flanzer (July, 1907, under the title " Uber 

 den gegenwartigen Stand und die Aus- 

 sichten der Guayule Industrie) (on the 

 present conditions and the prospects of 

 the Guayule industry)": From it the fol- 

 lowing observations may be added to 

 what has been said above. Dr. Endlich 

 recognises a central area of 75,000 square 

 Rm. (28,950 square miles) of Guayule land, 

 comprising the northern parts of Zaca- 

 tecas and San Luis Potosi, the eastern 

 part of Durango and the south of Coa- 

 huila. Then there are smaller areas in 

 Nueva Leon, Chihuahua, New Mexico, 

 Arizon, and Texas. About one-tenth of 



