888 CONTKIBUTIONS FEOM THE NATIONAL HEEBAKIUM. 



large joints often 4 to 5 cm. apart, when young bearing brown wool; spines 

 white, usually 1 to 5, slightly spreading, sometimes nearly porrect, usually only 

 2 to 3 cm. long, sometimes few and confined to tlie upper areoles ; glochids few, 

 yellow, caducous, sometimes appearing again on old joints ; flowers yellow 

 to orange, about 8 cm. broad; ovary spiny or spineless, obovoid; fruit 

 7 to 8 cm. long. " Nopal de Castilla." 



This is the species from which the best edible tunas are obtained. Many of 

 the varieties have local names. 



Opuntia trihuloides Griffiths ^ is a closely related form. 



82. Opuntia robusta Wendl. ; Pfeiff. Enum. Cact. 165. 1837. 

 Opuniia flavicans Lem. Hort. Monv. 61. 1839. 



Opuntia larreyi Weber; Coulter, Contr. U. S. Nat. Herb. 3: 423. 1896. 



Opuntia gorda Griffiths, Monatsschr. Kakteenk. 23: 134. 1913. 



Central Mexico. 



Often erect, sometimes 5 meters high, usually much branched; joints orbic- 

 ular to oblong, 20 to 25 cm. long, 10 to 12.5 cm. broad, very thick, bluish 

 green, glaucous ; spines 8 to 12, stout, very diverse, brown or yellowish at 

 base, white above, up to 5 cm. long ; flowers 5 cm. broad, yellow ; fruit globular 

 to ellipsoid, at first more or less tuberculate, deep red, 7 to 9 cm. long. " Tuna 

 tapona," " tuna camuesa." 



Opuntia albicans Salm-Dyck ° is said by Berger to be closely related to this 

 species. 0. mcgalartlira Rose,' known in Zacatecas as " rastrero," is closely 

 related; also O. cochinera Griffiths,* which is called " cochinera " in the same 

 state. 



83. Opuntia guerrana Griffiths, Rep. Mo. Bot. Gard. 19: 260. 1008. 

 Hidalgo, the type from Dublin. 



I'lants 90 to 120 cm. high, with an open branching top ; joints oblong to 

 orbicular, 15 to 25 cm. long, thick, glaucous; areoles 5 mm. in diameter, filled 

 with tawny wool ; spines white to yellow, 1 to 6, flattened, twisted ; petals 

 yellow ; fruit globose, greenish white, 4 to 5 cm. in diameter. " Nopal tapon." 



84. Opuntia stenopetala Eugelm. Proc. Amer. Acad. 3: 289. 1856. 

 Coahuila to Queretaro and Hidalgo ; type from Buena Vista, Coahuila. 

 Low bushy plant, often forming thickets, the main branches procumbent and 



resting on the edges of the joints ; joints obovate to orbicular, 10 to 20 cm. 

 long, grayish green, but often more or less purplish, very spiny; areoles often 

 remote, 1 to 3 cm. apart, the lower ones often without spines, bearing white 

 wool wlien young; spines usually reddish brown to black, but sometimes be- 

 coming pale, usually 2 to 4, the longest 5 cm. long, the larger ones somewhat 

 flattened ; glochids very abundant on young joints, brown ; flowers dioecious, 

 including the ovary only 3 cm. long; petals orange-red, very narrow, 10 to 12 

 mm. long, with long acuminate tips; ovary leafy, the upper leaves similar to 

 the sepals ; fruit globular, 3 cm. in diameter, acid, naked or spiny ; seeds 

 smooth, 3 mm. in diameter, with broad rounded margins. " Nopal lasar6n " 

 (San Luis Potosl) ; "nopal Colorado" (Zacatecas). 



* Monatsschr. Kakteenk. 23: 137. 1913. 



* Hort. Dyck. 361. 1834. 

 "Smiths. Misc. Coll. 50: 529. 1908. 

 *Rep. Mo. Bot. Gard. 19: 203. pi. 26. 1908. 



