942 CONTEIBUTIONS FEOM THE NATIONAL HERBAEIUM. 



I 



Plants much smaller, 60 cm. or less in diameter, sometimes forming large 

 clumps. 



Areoles with stout spines and weak bristles 16. F, robustus. 



Areoles with stout spines only. 

 Spines never hooked. 

 Spines all straight. 



Scales on ovary linear, with long-ciliate margins 20. F. flavovirens. 



Scales on ovary broader than linear, not with long-ciliate margins. 

 Flowers 4 to 5 cm. long; plants green. 



Plants flattened ; ribs acute ; margin of scales of ovary not cili- 



ate 17. F. echidne. 



Plants rounded ; ribs obtuse ; margin of scales of ovary cili- 



ate 18. F. alaniosanus. 



Flowers 2 cm. long; plants glaucous 19. F. glaucescens. 



Spines more or less curved. 



Flowers 3.5 cm. long or less ; ribs up to 24 21. F. melocactiformis. 



Flowers larger; ribs fewer. 



Scales on ovary acute 22. F. macrodiscus. 



Scales on ovary obtuse 23. F. viridescens. 



Spines, at least some of them, hooked or recurved at the tip. 

 Central spines, or one of them, broad and short. 



Central spine solitary 24. F. nobilis. 



Central spines several. 



Radial spines all straight 25. F. latispinus. 



Radial spines on lower side of areoles hooked_26. F. crassihamatus. 

 Central spines slender and elongate. 



Flowers large, yellow 27. F. hamatacanthus. 



Flowers small, pinkish to brownish 28. F. uncinatus. 



1. Ferocactus stainesii (Hook.) Britt. & Rose, Cactaceae 3: 124. 1922. 

 Echinocactus stainesii Hook.; Audot, Rev. Hort. 6: 248. 1845. 

 Echinocactus pilosus Galeotti ; Salm-Dyck, Cact. Hort. Dyck. 1849. 148. 1850. 

 San Luis Potosl. 



Simple or proliferous, globular, up to 1.5 meters high; ribs 13 to 20, com- 

 pressed, more or less undulate; areoles distant, circular; radial spines re- 

 duced to long white hairs; central spines several, subulate, at first purplish, 

 becoming pale yellow in age ; flowers yellow. 



2. Ferocactus pringlei (Coulter) Britt. & Rose, Cactaceae 3: 125. 1922. 

 Echinocactus pilosus pringlei Coulter, Contr. U. S. Nat. Herb. 3: 365. 1896. 

 Echinocactus pringlei Rose, Contr. U. S. Nat. Herb. 10: 127. 1906. 

 Coahuila and Zacatecas ; type from Jimulco, Ooahuila. 



Growing in clumps, becoming cylindric, sometimes 3 meters high and 30 to 

 40 cm. in diameter ; ribs usually 16 to 18, more or less compi'essed ; areoles 

 numerous, closely set or contiguous, the outer margin with a row of white or 

 straw-colored hairs 2 to 4 cm. long ; spines red, the three lower one^ slender, 

 almost acicular, the innermost much stouter, somewhat flattened, angular, 

 curved or nearly straight ; flowers red without, yellow within, 2.5 cm. long ; 

 scales on the ovary numerous, orbicular, imbricate; inner perianth segments 

 oblanceolate, obtuse or apiculate ; fruit yeUow, somewhat succulent, dehiscing 

 by a basal pore, 3 to 4 cm. long, crowned by the persisting perianth ; seeds 1.5 

 mm. long, brownish, pitted, with a small basal hilum. " Biznaga colorada " 

 (Zacatecas). 



