IOO 



THE CACTACEAE. 



Series 1. PUMILAE. 



Low, spiny species, with slightly flattened, narrowly cylindric or linear-oblong, readily detached 

 ultimate joints, the main stem terete. We know three species, the typical one in Mexico and Guate- 

 mala, one from Oaxaca, Mexico, and one Peruvian. In the structure of their joints they form a 

 transitional series between Cylindropuntia and Platyopuntia, and might be included in either of these 

 subgenera with about equal reason. 



KEY TO SPECIES. 



Young areoles with only i to 3 spines; joints 2 to 3 cm. thick. 



Plant i to 5 meters high; joints tubercled; spines yellowish. . . . . 77. O. pumila 



Plants about 2 dm. high; joints not tubercled; spines reddish to brown. . 770. O. depauperata 



Areoles with 3 to 7 spines; plants i to 4 dm. high. 



Joints i to 1.5 cm. thick; areoles not blotched; spines brownish . . . 78. O. pubescens 



Joints 2 to 3 cm. thick; young areoles dark-blotched; spines yellowish. . ... 79. 0. pascoensis 



FIG. 122. Opuntia pumila forming low thickets. 



77. Opuntia pumila Rose, Smiths. Misc. Coll. 50: 521. 1908. 



Stems low, very much branched, the joints readily falling off when touched, 6 to 20 cm. long, 

 velvety-pubescent, terete or sometimes slightly flattened, turgid, bearing more or less prominent 

 tubercles ; areoles small, those of old stems bearing several slender spines, the longer ones 3 cm. long ; 

 areoles of young joints usually bearing 2 yellowish spines; ovary pubescent, with few spines or none; 

 petals yellow, tinged with red, 15 mm. long; fruit globular, red, 15 mm. long. 



Type locality: Near Oaxaca City, Mexico, on the road to Mitla. 

 Distribution: Central and southern Mexico. 



When this species was described, attention was called to various forms which belonged 

 here or to one or more related species. These we now refer to 0. pubcsccns. 



Figure 122 is from a photograph of the type; figure 123 represents joints of the same. 



