84 



THE CACTACEAE. 



Fig. 98. — Opimtia grahamii. X0.75. 



white, turning brown, persistent on the old stems; flowers yellow, 5 cm. broad; sepals ovate, acute, 

 about 5 mm. long; fruit oblong to ovoid, 3 to 4.5 cm. long, its numerous areoles bearing white glochids 

 and some slender spines; seeds beakless, 5 to 5.5 mm. in diameter, the commissure indistinct, linear. 



Type locality: Near El Paso, Texas. 



Distribution: Western Texas, New Mexico, and 

 adjacent parts of IMexico. 



This species was named for James Duncan 

 Graham, Colonel, Corps of Engineers, United States 

 Army, who died December 28, 1865, at Boston, 

 INIassachusetts. Colonel Graham was for a time 

 chief of the scientific corps of the United States 

 and ^Mexican Boundary Commission, and caused 

 the specimens of this plant to be transmitted to Dr. 

 George Engelmann. 



The plant succeeds rather well in cultivation under glass. 



Illustrations: Cact. Mex. Bound, pi. 72; Schumann, Gesamtb. Kakteen f. 102. 



Figure 98 represents joints of a plant collected by Dr. Rose on hills near Sierra Blanca, 

 Texas, in 1913. 



Subgenus 2. TEPHRO CACTUS. 



Includes all the South American species of Opunlia which have short, oblong, or globular joints. 

 It is hardly to be distinguished from the North American series Clavatae. Four series are recog- 

 nized. The plants are confined to Peru, Chile, Bolivia, and .\rgentina. (See key to series, p. 44.) 



Series 1. WEBERIANAE. 

 Plants low, forming dense clumps; joints subcylindric, strongly tuberculate and bearing numer- 

 ous spines. This series suggests Platyopuntia, while the other series show closer relationship with 

 the Cylindropuntia. Only one species known, inhabiting the dry part of northern Argentina. 



55. Opuntia weberi Spegazzini, Anal. Mus. Nac. Buenos Aires III. 4: 509. 1905. 



Densely cespitose, forming clumps 2 to 3 dm. in diameter and 10 to 18 cm. high; joints yellomsh 

 green, erect, cyUndric, strongly tuberculate, 2 to 6 cm. long, 1.5 to 2 cm. in diameter, densely spiny; 



Fig. 99. — Opuntia weberi as it grows wild. 



