STANDLEY TREES AND SHRUBS OF MEXICO. 875 



17. Opuntia tunicata (Lehm.) Link & Otto; Pfeiff. Enum. Cact. 170. 1837. 

 Cactus tunicatus Lehm. Ind. Sem. Hort. Hamb. 6. 1827. 



Opuntia stapeliae DC. Mem. Mus. Hist. Nat. 17: 117. 1828. 



Opuntia perrita Griffitlis, Rep. Mo. Bet. Gard. 22: 33. 1912. 



Widely distributed in Central Mexico. Ecuador, Peru, and Cliile. 



Very variable, sometimes low and spreading from the base and form- 

 ing broad clumps, at other times 50 to 60 cm. high, with a more or less 

 definite woody stem and numerous lateral branches; joints easily detached, 

 sometimes short and nearly globular to narrowly oblong, 10 to 15 cm. long; 

 spines reddish, normally 6 to 10, 4 to 5 cm. long, covered with thin white 

 papery sheaths ; flowers 3 cm. long, yellow ; petals obtuse ; ovary often bear- 

 ing long spines at the areoles, but usually naked. " Abrojo " (Mexico); 

 *' clavellina " (Durango) ; " tencholote " (Ochoterena). 



18. Opuntia pallida Rose, Smiths. Misc. Coll. 50: 507. 1908. 

 Hildalgo ; type from Tula. 



Stems 5 cm. in diameter, about 1 meter high, with widely spreading 

 branches, the whole plant often broader than high ; old areoles very spiny, 

 often bearing 20 spines or more, often 3 to 4 cm. long, with white papery 

 sheaths ; young areoles bearing few spines ; ovary tuberculate, tlie areoles 

 either naked or bearing a few bristly spines ; flowers pale rose-colored ; 

 petals 15 mm. long. 



19. Opuntia molesta T. S. Brandeg. Proc. Calif. Acad. II. 2: 164. 1889. 

 Baja California, the type from San Ignacio. 



Stems 1 to 2 meters high, with few long spreading branches ; joints clavate 

 to subcylindric, 10 to 40 cm. long, sometimes as much as 4 cm. in diameter 

 at the top, pale green, with low broad tubercles, these elongate and often 

 4 cm. long or more; spines 6 to 10, unequal, tlie longest 2.5 to 5 cm. long, 

 straw-colored, with loose papery sheaths ; flowers purple, 5 em. in diameter ; 

 fruit ovoid, 2.5 cm. long, somewhat spiny or naked; seeds 6 mm. in di- 

 ameter, irregular in shape. 



20. Opuntia f ulg-ida Engelm. Proc. Amer. Acad. 3 : 306. 1856. 

 Opuntia mamillata Schott ; Engelm. Proc. Amer. Acad. 3: 308. 1856. 

 Sinaloa and Sonora ; type from western Sonora. Arizona. 



Plants sometimes 3 meters high or even larger, with a rather definite woody 

 trunk 10 to 20 cm. in diameter, much branched, sometimes almost from the base 

 and forming a compact flattened crown ; terminal joints 10 to 20 cm. long, 



3 to 5 cm. in diameter, very succulent, strongly tuberculate, easily breaking 

 off ; spines 2 to 12, yellowish to brown, 2.5 to 3.5 cm. long, acicular, covered with 

 loose papery sheaths ; glocliids small, whitish to light yellow ; flowers light 

 rose, 2.5 to 3 cm. broad ; fruit at first tuberculate, in age smooth, somewhat 

 pear-shaped, 2 to 5 cm. long, green, usually very proliferous ; seeds rather small, 



4 mm. broad, often wanting. " Velas de coyote" (Coulter). 



21. Opuntia spinosior (Engelm.) Tourney, Bot. Gaz. 25: 119. 1898. 

 Opuntia whipplei spinosior Engelm. Proc. Amer. Acad. 3: 307. 1856. 

 Sonora. New Mexico and Arizona. 



Plants 2 to 4 meters high, treelike, with a more or less definite woody trunk, 

 openly branched ; ultimate joints 10 to 30 cm. long, 1.5 to 2.5 cm. in diameter, 

 often bright purple, strongly tuberculate; tubercles about 6 to 12 mm. long, 

 longer than broad, more or less flattened laterally ; spines 6 to 12, but on old 

 branches sometimes as many as 25, 10 to 1.^ mm. long, divergent, gray to brown- 

 ish, covered with thin sheaths ; glochids yellowish white ; flowers 5 to 6 cm. 



