Problems in the Development and 
Utilization of Arid Land Plants 
PM RUETZ 
Agricultural Research Service, United States De- 
partment of Agriculture, Beltsville, Maryland 
Native plants of the desert region of the southwestern United 
States and northern Mexico, in addition to contributing much to 
the health and well-being of the inhabitants, have long held the 
attention of chemists and biologists as potential sources of indus- 
trial raw materials. Although attention has been directed to 
many of the species as containing exploitable quantities of essen- 
tial oils, medicinal alkaloids, gums, fibers, rubber, tannin and 
other products (4, 5), very few of them have been studied thor- 
oughly to determine their chemical constituents. An even smaller 
number, represented by guayule (Parthenium argentatum) for 
rubber (7), and canaigre (Rumex hymenosepalus) for tannin (6), 
have been investigated by chemists, plant breeders, and engi- 
neers attempting to improve the plants and the methods of 
processing to the point where they can be utilized in commerce, 
either as wild plants or cultivated crops. 
Conditions of Commercial Use 
Unless the plant product involved is scarce or has unique 
properties demanded by a particular industry, it must be pro- 
duced on a competitive cost basis with similar products from 
other sources. Furthermore, it must be available in sufficient 
quantity to furnish a fairly continuous supply to commercial 
users. Candelilla wax, from species of Euphorbia and Pedilanthus, 
is an example of a desert plant product which has been in com- 
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