880 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



41. Opuntia comonduensis (Coulter) Britt. & Rose, Smiths. Misc. Coll. 50: 

 519. 1908. 



Opuntia angustata comonduensis Coulter, Contr. U. S. Nat. Herb. 3: 425. 1S9G. 



Baja California ; type from Comondti. 



Low spreading plants, sometimes 20 cm. high and forming broad clumps ; 

 joints obovate to orbicular, 12 to 15 cm. long, softly pubescent ; areoles large, 

 filled with brown wool and yellow glochids ; lower areoles spineless, the 

 upper ones bearing 1 or 2, rarely 3, or on old stems as many as 10, slender 

 spines, 3 to 5 cm. long or longer, yellow; flowers (including ovary) 6 cm. 

 long, yellow ; fruit purple, ^ cm. long, spineless ; seeds 4 to 4.5 mm. broad, 

 thick. 



42. Opvmtia megarhiza Rose, Contr. U. S. Nat. Herb. 10: 126. 190G. 

 San Luis Potosi ; tyjte from Alvftrez. 



Roots long and thickened, sometimes 30 to 60 cm. long and 5 to 6 cm. in 

 diameter; stems 20 to 30 cm. high, much branched; lower joints elongate, 20 

 to 30 cm. long, cuneate below, thin, 3 cm. broad ; lateral joints appearing along 

 the margins of the older joints and often, if not always, in the same plane; 

 spines 2 to 4, acicular, 1 to 2.5 cm. long, brown ; flowers lemon-yellow, often 

 tinged with rose, 5 cm. broad ; petals about 13, obovate, mucronately tipped ; 

 ovary clavate, 3 cm. long. 



Palmer reports that the fleshy roots are applied as poultices for the re- 

 duction of fractures and inflammation. 



43. Opuntia pottsii Salm-Dyck, Cact. Hort. Dyck. 1849. 236. 1850. 

 Chihuahua. Texas and New Mexico. 



Low spreading plant, 30 cm. high or less, from thickened tuberous roots 2 

 to 3 cm. in diameter, these sometimes moniliform ; joints broadly obovate, 3.5 

 to 12 cm. long, pale green to bluish ; areoles few, either small or large ; spines 

 confined to the upper and marginal areoles, 1 or 2, slender, 2 to 4 cm. long, 

 usually white but sometimes purplish ; glochids yellow, usually few but some- 

 times abundant ; flowers 6 to 7 cm. broad, deep purple ; ovary slender, 3 to 

 3.5 cm. long, with only a few scattered areoles ; fruit spineless. 



44. Opuntia setispina Engelm. ; Salm-Dyck, Cact. Hort. Dyck. 1849. 239. 1850. 

 Chihuahua ; type from mountains west of Chihuahua. 



Stems branching and spreading, sometimes forming clumps a meter broad, 

 erect and 60 cm. high ; joints deep bluish green, somewhat glaucous, often 

 purplish at the areoles, obovate to orbicular, 5 to 15 cm. in diameter ; spines 

 1 to 6 from an areole, white, 2 to 3 cm. long ; glochids yellow, very conspicuous 

 on old joints ; flowers yellow ; fruit purplish, about 4 cm. long. 



45. Opuntia tenuispina Engelm. Proc. Amer. 3 : 294. 1856. 

 Opuntia minor C. Muell. Ann. Bot. Syst. Walp. 5: 50. 1858. 

 Northern Mexico. Western Texas to Arizona ; type from El Paso. 



Low and spreading but becoming 30 cm. high; joints obovate, attenuate at 

 base, 7 to 15 cm. long, light green ; spines 1 to 3 from an areole, slender, usu- 

 ally white but sometimes brownish, 3 to 5 cm. long, the upper spines erect or 

 spreading ; glochids brown : flowers yellow, 6 to 7.5 cm. broad ; ovary with 

 numerous areoles filled with brown wool and brown glochids; fruit oblong, 

 2.5 to 4 cm. long ; seeds 4 mm. broad or less, very irregular. 



46. Opuntia macrocentra Engelm. Proc. Amer. Acad. 3: 292. 1856. 

 Chihuahua. Arizona to western Texas. 



Somewhat bushy, with ascending branches, 60 to 90 cm. high ; joints orbicular 

 to oblong, or sometimes broader than long, 10 to 20 cm. long, often bluish or 



