Addisonia 19 



(Plate 90) 



OPUNTIA LASIACANTHA 

 Slender White-spined Prickly Pear 



Native oj central and southern Mexico 



Family Cactaceab Cactus Family 



Opuntia lasiacantha Pfeiffer, Enum. Cact. 160. 1837. 



Opuntia megacantha lasiacantha Berger, Bot. Jahrb. 36: 453. 1905. 



}Opuntia chaetocarpa Griffiths, Proc. Biol. Soc. Wash. 27: 25. 1914, 



A large and much-branched cactus, six feet high or higher, the 

 lower, trunk-like part sometimes becoming eight inches thick. The 

 joints are flat, dull-green, about a foot long or less, often eight inches 

 wide, and scarcely half an inch thick; the areoles are small and cir- 

 cular, mostly an inch or more apart; the leaves are minute, reddish, 

 awl-shaped, and fall away early. There are from one to fom- needle- 

 like spines at most of the younger areoles, which diverge from the 

 joints at rather wide angles; the spines are white, with somewhat 

 brown or blackish tips, and they are about two inches long or less, 

 one of them usually much longer than the others ; old areoles develop 

 more numerous spines, sometimes as many as fifteen, and they fade 

 grey; the glochids are yellowish to brown and form a tuft at the upper 

 part of each areole, just above the spines, when young about one 

 eighth of an inch long, but twice that length when old. The flowers 

 appear singly at areoles on the edges of the joints near the top; the 

 ovary is obovoid, nearly one inch long, and rather more than half an 

 inch thick; the sepals are about half an inch long, ovate and pointed; 

 the spreading petals are about fifteen in number and from one inch 

 to one and a half inches in length, obovate, variously pointed, 

 rounded or notched at the apex, and narrowed or wedge-shaped at 

 the base; in color they are described as yellow or orange on different 

 plants, in this color-difference agreeing with several other species of 

 Opuntia; the numerous yellow stamens are less than half as long as 

 the petals; the style is pink and the stigma-lobes green. The fruit 

 is a globose-obovoid, red berry, nearly two inches long, with a deeply 

 sunken top, its areoles bearing a tuft of short glochids and an occa- 

 sional bristle. 



This cactus appears to have a wide range in the dry parts of central 

 and southern Mexico; it is a member of the group of white-spined 

 prickly pears (tunas) yielding edible fruits which are important as 

 food in Mexico and are exported; the fruit of 0. lasiacantha is, how- 

 ever, not of the best quality. Many races of this group of prickly 

 pears are cultivated for their fruits and have thus been crudely se- 

 lected; their botanical classification is very difficult and it is perhaps 

 impossible to define accurately the really wild species. 



