ARID LAND PLANTS 417 
The development of effective methods of production also has 
an important bearing on the success of any program for convert- 
ing wild plants into cultivated crops. Early experiments with 
canaigre indicated that two full growing seasons were necessary 
to produce economic yields of roots with satisfactory quality. In 
recent experiments, 1§ tons of roots per acre, equivalent to ap- 
proximately 1,800 pounds of 100% tannin, has been produced in 
one 10-month growing season. Other results indicate that even 
higher yields may be obtained from improved strains, using 
either seed or crowns for planting stock. 
Soil moisture is the major factor which regulates the volume 
of roots produced by wild canaigre plants. The storage roots sur- 
vive long periods of extremely low soil moisture, increasing in 
size and number only during favorable seasons. As a cultivated 
crop in southern Arizona, canaigre requires a limited amount of 
irrigation to produce satisfactory yields. Adequate soil moisture 
must be available during October and November to establish the 
plants, and during March and April to promote root growth and 
tannin storage. Further study of the seasonal development of 
canaigre in relation to soil moisture may be expected to lead to 
more effective methods of using limited supplies of irrigation 
water. 
The processing of canaigre roots into high quality tanning ex- 
tracts presented several major problems because of the presence 
of sugar and starch in the roots. Research on processing, con- 
ducted concurrently with the breeding and production investiga- 
tions, has resulted in the development of methods for producing 
tanning extracts which compare favorably with commerical ex- 
tracts in tannin content and tanning properties (6). Tonnage lots 
of canaigre extract will be available in the near future for use in 
semi-commerical tanning tests. 
The progress that has been made in developing canaigre for a 
source of vegetable tannin for industry illustrates one method of 
attacking the problem of utilizing arid land plants. Such progress 
can be achieved only through expensive research on the part of 
chemists, plant breeders, agronomists, and engineers. Ideally, it 
should be a cooperative enterprise involving appropriate public 
