872 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



5. Opuntia recondita Griffiths, Monatsschr. Kakteenk. 23: 131. 1913. 



Type from La Perla, Mexico. 



Slirub 1 to 1.5 meters high ; joints 20 to 30 cm. long, very spiny, about 2 cm. 

 in diameter, tuberculate ; areoles broadly obovate, .5 to 6 mm. long, in age 

 larger and more prominent, forming new wool for several years ; glochids yel- 

 low ; spines at first 2 to 4, later 6 to 10, 2.5 to 5 cm. long, gray at base, deep 

 reddish brown at tip, with a loose sheath ; flowers bright purple, 2.5 cm. broad ;. 

 fruit persistent, 8 to 3.5 cm. long, greenish yellow, weakly tuberculate. 



e. Opuntia thurberi Engelm. Proc. Amer. Acad. 3: 308. 1856. 



Sonora and Sinaloa ; type from Bacuachi, Sonora. Arizona. 



Large bushy plants, 2 to 4 meters high ; joints slender, elongate, 15 to 25 cm. 

 long, 10 to 12 mm. in diameter ; tubei'cles 1.5 to 2 cm. long, flattened laterally ; 

 spines 3 to 5, short (10 to 12 mm. long), spreading, covered with thin brown 

 papery sheaths, the lowest one stoutest ; flowers 3.5 cm. broad, brownish ; fruit 

 2 to 3 cm. long, spineless ; seeds nearly globular, 4 mm. in diameter. "Cliolla " 

 (Sinaloa). 



7. Opuntia clavellina Engelm.; Coulter, Contr. U. S. Nat. Herb. 3: 444. 1896. 

 Central Baja California ; type collected near Misi6n Purisima. 



Plants 1 meter high, rather openly branched ; ultimate joints slender, spread- 

 ing or ascending, somewhat clavate, 5 to 10 cm. long, a little over 1 cm. in 

 diameter; tubercles prominent, elongate; spines 3 to 6 in a cluster, very 

 long, covered with loose, straw-colored or brown sheaths, the central one much 

 longer and porrect ; flowers yellow ; fruit clavate, short, tuberculate. 



For an illustration of this species see Contr. U. S. Nat. Herb. 16: pi. 129, A. 



8. Opuntia echinocarpa Engelm. & Bigel. Proc. Amer. Acad. 3: 305. 1856. 

 Baja California. Southwestern United States ; type from the Colorado Val- 

 ley near the mouth of the Bill Williams River. 



Plants usually low, but sometimes 1.5 meters high, much branciied and 

 widely spreading, with a short woody trunk 2 to 3 cm. in diameter, in age 

 with nenrly smooth bark; joints short, turgid, strongly tuberculate; spines 

 numerous, when young bright yellow, when older brownish or in age grayish, 

 unequally covered with thin papery sheaths ; flowers yellowish, but the sepals 

 often tipped with red ; ovary short, turbinate, densely spiny, especially in the 

 upper part ; fruit dry, very spiny ; seeds somewhat angular, 4 mm. broad. 



Opuntia acanthocarpa Engelm. & Bigel.,* a somewhat smaller species, has 

 been reported from Mexico, but we have seen no specimens. 



9. Opuntia serpentina Engelm. Amer. .Tourn. Sci. IL 14: 338. 1852. 

 Northern Baja California. Southern California, the type from San Diego. 

 Ascending, erect, or prostrate; branches slender, 2 to 2.5 cm. in diameter, 



bluish green, strongly tuberculate ; tubercles elevated, 1 to 1.5 cm. long, longer 

 than broad, flattened ; spines 7 to 20, brown, covered with yellowish brown, 

 papery sheaths about 1 cm. long ; glochids light brown ; flowers close together 

 at the top of short branches, about 4 cm. broad, greenish yellow, the outer petals 

 tinged with red ; ovary strongly tuberculate, spiny, with a depressed umbilicus ; 

 fruit dry, very spiny. 



10. Opuntia big-elovii Engelm. Proc. Amer. Acad. 3: 307. 1856. 



Northern Sonora and northern Baja California. Southwestern United States; 

 type from the region of Bill Williams River. 



Usually with a central erect trunk, 1 meter high or less, with short lateral 

 branches, the upper ones erect; joints usually 5 to 15 cm. long, very turgid, 



iProc. Amer. Acad. 3: 308. 1856. 



