BEHAVIOR OF SPECIES OF CACTI. 5 



zero temperatures, they are more promising for breeding purposes 

 than 0. lindheimeri itself. 



On the coast of California from Santa Barbara south and extend- 

 ing into Lower California occurs a species which has usually passed 

 for Opuntia occidentalis. It differs very decidedly, however, from 

 this species in many particulars. Its joints are oval to lenticular and 

 pointed at either end. It is, in general, a very spiny species, but 

 frequently spineless or nearly spineless joints are produced. Mrs. 

 Brandegee has called attention to this condition in a general way 

 on one or two occasions. The attention of the writer was first called 

 to it also at San Diego, Cal., a number of years ago, in a plant which 

 was studied on two different visits two years apart. From this plant 

 spineless joints were set at San Antonio, Tex., but the species proved 

 to be not perfectly hardy out of doors. The plants, however, are 

 seldom killed outright. Some selections have been made from this 

 original collection made in 1905. On three occasions spineless cut- 

 tings have been selected and set in the open ground. Spineless cut- 

 tings have also been taken from the progeny of the same cuttings 

 and set under winter protection at San Antonio and in the open 

 ground at Brownsville, Tex. They have also been established 

 recently from the latter situation at Chico, Cal. 



Invariably in all of these experiments spiny joints have grown 

 from the spineless ones, but frequently a spineless joint is produced 

 and in about the same proportion as in the original plant. The 

 selections made appear to have no effect upon this character. 



The character and the degree of spinelessness are peculiarly inter- 

 esting in this species. The common areoles, or cushions of spines 

 (fig. 1, p. 2), are of good size, measuring one-fourth of an inch in di- 

 ameter, and have spines averaging one-half to 1 inch in length and 

 from three to five in number. They are stout and formidable. In 

 the spineless joints the areole is very much contracted and a little 

 sunken, a condition which is easily recognizable in the young state 

 when the joint is only half grown. As a matter of fact, completely 

 spineless joints are somewhat rare. They are sometimes found, 

 however, but more commonly there are one to a few areoles toward 

 the end of the joint which have the normal number of spines and 

 spicules, while the remainder may be nearly or quite free of both. 

 At other times an equatorial section or an upper or lower half may 

 be spineless or have spines decidedly reduced, while the remainder 

 is normally spiny. 



At San Antonio, Tex., the species grows very rapidly, usually mak- 

 ing branches three joints in length from cuttings set in the spring. 

 Usually there will be produced one cutting to a limb entirely or par- 

 tially spineless. It is therefore possible to make selection from vege- 

 tative parts each season. At Brownsville the species does not grow 



