3 ° 
400 to 700 pounds, taking an average for large areas. This is 
undoubtedly too high an average. By actual count in very favour- 
able localities J have become convinced that even under the best 
conditions not more than 1,500 pounds can be obtained per acre from 
the Guayule patches, and these constitute less than one-tenth of 
the total area of the territory, where the plant occurs. That my 
estimation in this regard is upheld by others who have investigated 
the matfer and expressed an unbiased opinion is shown by the 
following lines, translated from an article by Dr. R. Endlich, in 
u Der Tropenpflanzer.” The author says in part:—. 
“The supply of the Gupyule is very unevenly distributed in 
the territory the plant occupied. In most places the plants are 
^isolated, growing sometimes in large and 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 specimens. 
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 in size and weight are so great that in 
places where the plants are small and grow close together ten 
t plants have a weight of only one kilogram ( = 2 1/5 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 
(1 1/10 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 considerable, 
and must be taken into consideration.” 
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. 
C 
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 illusionary to speak of 
growing the Guayule plant for Commercial 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 uncertainty about the germination of the 
seeds brings in such an element of chance, that indeed very much 
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