876 CONTRIBUTIONS FEOM THE NATIONAL HERBARIUM. 



broad, purple to pink, yellow, or even white ; petals about 10, broad at apex, 

 narrowed at base; ovary tuberculate, bearing small purple leaves and long, 

 white, easily detached bristles ; fruit strongly tuberculate, spineless, yellow, glo- 

 bose to broadly oblong, 2.5 to 4 cm. long, with a depressed umbilicus ; seeds 

 white, 4 mm. broad, smooth, with a very indistinct marginal band. 



22. Opuntia prolifera Engelm. Amer. Journ. Sci. II. 14: 338. 1852. 

 Widely distributed in Baja California. Southern California, the type from 



San Diego. 



Stems 1 to 2 meters high, the trunk and old branches terete and woody; 

 terminal joints 3 to 12 cm. long, easily breaking off, fleshy, covered with short, 

 more or less turgid tubercles ; spines 6 to 12, brown, 10 to 12 mm. long ; glochids 

 pale ; flowers small ; sepals orbicular, obtuse, dark red ; petals red ; ovary 1 

 cm, long, strongly tuberculate, the upper areoles bearing 2 to 6 reddish spines, 

 or the joints naked throughout ; fruit proliferous, 3 to 3.5 cm. long, often with- 

 out seeds. 



23. Opuntia alcahes Weber, Bull. Mus. Hist. Nat. 1: 321. 1895. 

 Baja California. 



Plants about 1 meter high, much branched, very spiny, especially when old; 

 branches terete ; spines on young joints about 12, short, covered with white or 

 very pale sheaths ; tubercles prominent, diamond-shaped ; sepals small, brownish, 

 closely imbricate, hardly spreading at tips; petals sometimes wanting, if 

 present about 1 cm. long, greenish yellow, obtuse; fruit globular, small, be- 

 coming turgid in age, yellowish, more or less proliferous, the umbilicus trun- 

 cate or slightly depressed. 



24. Opuntia burrageana Britt. & Rose, Cactaceae 1: 70. 1919. 

 Baja California, the type from Pichilinque Island. 



Usually low and bushy, rarely 1 meter high ; stems slender, 1 to 2 cm. Ln 

 diameter, densely spiny ; young joints cylindric to narrow-clavate, 15 cm. long 

 or less ; areoles closely set ; tubercles rather low, not much broader than long ; 

 spines numerous, similar, spreading, rarely 2 cm. long, all covered with thin, 

 bright yellow sheaths ; wool in areoles short, brown ; glochids, when present, 

 short, light yellow ; flower 3 to 4 cm. broad ; petals few, brownish red with 

 green base; ovary very spiny; fruit not proliferous, globular, 2 cm. in di- 

 ameter, somewhat tuberculate, probably dry ; seeds pale, 4 mm. in diameter. 



25. Opuntia invicta T. S. Brandeg. Proc. Calif. Acad. II. 2: 163. 1889, 

 Central Baja California; type from San Juanico. 



Plants usually growing in large clusters 2 meters in diameter and 20 to 50 

 cm. high, with many ascending or spreading branches; joints obovoid to 

 clavate, dark green, 8 to 10 cm. long, strongly tuberculate; tubercles large, 

 flattened laterally, 3 to 4 cm. long; areoles large, 1 to 1.5 cm. in diameter; 

 spines very formidable, when young reddish or purple with carmine-red 

 bases, chestnut-brown at tips and grayish between, in age dull ; radial spines 

 6 to 10; central spines 10 to 12, much stouter than the radials, strongly 

 flattened, the wool white; glochids few, white, 2 to 4 mm. long; flowers 

 yellow, 5 cm. in diameter ; sepals ovate, acuminate ; ovars'^ 2 cm. in di- 

 ameter, almost hidden by the numerous reddish acicular spines; seeds yel- 

 lowish, 2 mm. broad, 



26. Opuntia stanlyi Engelm. in Emory, Mil. Reconn. 158. 1848. 

 Opuntia emoryi Engelm. Proc. Amer. Acad. 3: 303. 1856. 

 Opuntia kunzei Rose, Smiths. Misc. Coll. 50: 505. 1908. 

 Northern Sonora. Arizona and New Mexico. 



