STANDLEY TREES AND SHRUBS OF MEXICO. 965 



2. Coryphantha runyonii Britt. & Rose, Cactaceae 4: 26. 1923. 



Along the Rio Grande in Texas, from Brownsville to Rio Grande City, and 

 doubtless occurring on the Mexican side of the river. 



Forming low clumps, sometimes 50 cm. in diameter, grayish green ; tubercles 

 1 to 2 cm. long, terete or somewhat flattened, grooved above for half their 

 length ; radial spines 6 or more, spreading, acicular, 3 cm. long or less, some- 

 times all yellow or sometimes one or more brown ; central spine on young 

 plants solitary, on old plants sometimes 2 or 3, up to 6 cm. long ; flowers purple, 

 6 cm. broad ; outer perianth segments ciliate, the inner ones spatulate-oblong, 

 acute ; fruit green ; seeds brown. 



3. Cor3rphantha ottonis (Pfeiff.) Lem. Cact. 34. 1868. 

 Mammillaria ottonis Pfeiff. Allg. Gartenz. 6: 274. 1838. 



MammiUaria bussleri Mundt ; Schum. Monatsschr. Kakteenk. 12: 47. 1902. 



Mammillaria golziana Haage, Monatsschr. Kakteenk. 19: 100. 1909. 



Central Mexico; type from Mineral del Monte, Hidalgo. 



Simple, globular to short-cylindric, 12 cm. high or less, 8 cm. in diameter, 

 glaucous to gray-green ; radial spines 8 to 12, nearly equal, 8 to 10 mm. long ; 

 central spines 3 or 4, longer and a little stouter than the radials ; axils of 

 flowering tubercles woolly; flowers white, 4 cm. long; outer perianth seg- 

 ments oblong, obtuse, the inner ones apiculate. 



4. Coryphantha recurvata (Bngelm.) Britt. & Rose, Cactaceae 4: 27. 1923. 

 Mammillaria recurvispina Engelm. Proc. Amer. Acad. 3: 266. 1856. Not 



M. recurvispina De Vriese, 1839. 



Mammillaria recurvata Engelm. Trans. Acad. St. Louis 2: 202. 1863. 



Sonora. Arizona. 



Plant body depressed-globose, 10 to 20 cm. in diameter, often forming large 

 masses 30 to 90 cm. in diameter and sometimes with over 50 heads; tubercles 

 low ; radial spines about 20, yellow to gray, with dark tips, pectinate, recurved ; 

 central spines 1, rarely 2, longer and darker than the radials, 12 to 20 mm. 

 long, more or less reflexed, often appressed ; flowers 25 to 35 cm. long, said 

 to be brownish outside ; inner perianth segments lemon-yellow. 



5. Coryphantha poselgeriana (Dietr.) Britt. & Rose, Cactaceae 4: 28. 1923. 

 Echinocactus poselgerianus Dietr. Allg. Gartenz. 19: 346. 1851. 

 Echinocactus saltillensis Poselger, Allg. Gartenz. 21: 101. 1853. 

 Echinocactus salinensis Poselger, Allg. Gartenz. 21: 106. 1853. 

 Mammillaria difflcilis Quehl, Monatsschr. Kakteenk. 18: 107. 1908. 

 Mammillaria valida Purpus, Monatsschr. Kakteenk. 21. 97. 1911. Not M. 



valida Weber. 1898. 



Coahuila and Zacatecas ; type from Saltillo, Coahuila. 



Plant body large for the genus, globular, bluish green ; tubercles large, 

 closely packed together and at base strongly angled ; radial spines of two 

 kinds, the 4 or 5 lower ones spi'eading, subulate, reddish to black, about as 

 long as the single central one (2 to 4 cm. long), the upper radials 5 to 8, 

 ascending, yellowish with black tips, weak, acicular ; flowers 4 to 5 cm. long 

 and nearly as broad when expanded ; flesh-colored ; segments spatulate, 

 usually rounded at apex; fruit oblong, 15 mm. long; seeds brownish. 



6. Coryphantha muehlenpfordtii (Poselg.) Britt. & Rose, Cactaceae 4: 28. 



1923. 

 MammiUaria sclieeri Miihlenpf. Allg. Gartenz. 15: 97. 1847. Not M. scheeri 



Miihlenpf. 1845. 

 Echinocactus muehlenpfordtii Poselg. Allg. Gartenz. 21: 102. 1853. 

 Chihuahua. Texas and New Mexico. 



