HARDIER SPINELESS CACTUS 



Present Commercial Varieties of Prickly Pear Suited to Very Limited Range- 

 Selection of Favorable Variations in Native Species Gives Promise of 

 Providing Forms That Will Stand Zero Temperature. 



David (jRiffiths 

 Bureau of Plant Industry, l'. S. Department of Agrieiilture, WasJiington, D. C 



IX a consideration of spineless prickly 

 pear culture on anything like a 

 comprehensive scale, the first and 

 most important necessity consists in 

 making it ajjijlicable to a greater 

 territory. At present, the crop is not 

 to be considered in our southwest, 

 except in California and the least frosty 

 portions of Arizona. It is not to be 

 thought of in New Mexico, nor Texas, 

 except in the southernmost extremity; 

 and the indications are that it can be 

 only imperfectly grown on our gulf 

 coast, and is adapted to only a portion 

 of the coastal region of Florida. So far 

 as the mainland of the United States 

 is concerned, then, there is only a com- 

 paratively small territory to which the 

 present spineless varieties arc applicable. 



The limiting factor is one of tempera- 

 Lure, the ]:)lants not being able to endure 

 temjx'ratures any lower than the orange. 

 Just where the danger point lies is as 

 difficult to state as it is with any other 

 crop; because contril)Uting factors are 

 numennis, jjoorly understood, and ex- 

 ceedingly influential in varying the 

 effect of gix'cn temjjeratures. 



During the January freeze of 1913, 

 in California, the Department's col- 

 lection was subjected to a temperature 

 of 13° F. for at most but a few hours; 

 only two or three s])ineless .sjiccies 

 escaped injury, the majority being 

 very severely hurt and all young i)lants 

 as a rule killed. In previous years, the 

 same collection has been severely injured 

 by temperatures of 20° of longer dura- 

 tion. During the freeze of 1913, on 

 the other hand, one of the Dejjartment's 

 cooperators at Lakeside, California, 

 had an actual record of <S° V. in one of 

 his cactus jjlantings, and the injury 

 done was negligible. In oik' of the 



182 



Department's plantings at San An- 

 tonio, Texas, a temperature of 20° F. 

 with sub-freezing weather for 24 hours 

 has always ])roved fatal to all of the 

 conventional sjiincless species now so 

 abundant in California, and so widely 

 advertised in the South and Southwest 

 generally. 



From this brief survey, it will be 

 readih' seen that exact temperatures 

 give us no more information with this 

 ero]) than with an\- other. Tlie data 

 of value here as with other crojjs is 

 gained from actual growing records. 

 The region in which the plants succeed 

 is the one to which the crop is adapted. 

 The variovis varieties have now been 

 tested over a wide enough territory 

 so that we are able with certainty to 

 limit the crop as at present constituted 

 to the region suggested above. 



BASIS FOR IMl'ROVE.MKNT. 



At the ijre.scnt time, there is in this 

 eountr\' a considerable wealth of ma- 

 terial to work with. There arc four 

 or five good botanical species of rapid- 

 growing spineless prickly pears. These 

 in turn can be divided still further into 

 what would in other groups be recog- 

 nized as at least twice that lunnber of 

 horticultural varieties. Besides these 

 10 or more fonns already spineless, 

 there are not far from 100 species of all 

 grades of spininess having qualities 

 which \Aacc them in the economic class 

 and make them of economic jiossibility. 

 But since we have in mind mainly the 

 production of spineless fomis suitable 

 for colder territory, sjiecies apj)lical)le 

 to (jur use become very much restricted 

 in numbers. For reasons which will 

 bi'come api)arenl later, our hopi-s ceiitei' 



