BULLETIN OF THE 



No. 31 



Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief 

 December 30, 1913. 



BEHAVIOR, UNDER CULTURAL CONDITIONS, OF 

 SPECIES OF CACTI KNOWN AS OPUNTIA. 



By David Griffiths, 

 Agriculturist, Office of Farm Management, Bureau of Plant Industry. 



INTRODUCTION. 



The investigations upon which the observations recorded in this 

 paper are based are being conducted in three principal localities — 

 Brownsville and San Antonio, Tex., and Chico, Cal. At each place 

 between 600 and 1,500 varieties of prickly pear and cane cacti have 

 been planted and grown well toward maturity or have failed to grow. 

 With such an array of material, secured from all the prickly-pear 

 regions of the world and representing especially that large stretch 

 of territory between Calgary, Canada, and Oaxaca, Mexico, there is 

 naturally a large quantity of data on various phases of the subject 

 accumulating very rapidly. 



In this paper are detailed a few of the salient features of con- 

 spicuous behavior. In the main, the points discussed here have a 

 bearing upon some of the economic aspects of this group of plants. 



While it is neither necessary nor desirable to enter into details at 

 the present time regarding the conduct of the work, that being re- 

 served for a future publication, a few words of explanation are de- 

 sirable. At Chico. where the main collection is now handled, work 

 is carried on both in the field and under sash shelters; at San An- 

 tonio in the field and under canvas shelters, and at Brownsville in the 

 field entirely, thus far. 



SPINE VARIATION. 



To treat the subject of spine variation adequately would require a 

 book of no small magnitude, but only a few phases of the subject will 

 be attempted at present. 



In the economic handling of the prickly pear as a farm crop in 



southern Texas great differences have been found in the ease with 



which spines are burned from different species, and the differences 



are to a considerable extent matters of geographical position. Native 



9761°— 13 1 



