STANDLEY TREES AND SHRUBS OF MEXICO. 947 



21. Ferocactus melocactiformis (DC.) Britt. & Rose, Cactaceae 3: 138. 1922. 

 Echinocactus melocactiformis DC. Prodr. 3: 462. 1828. 



Ecliinocactus histrix DC. M§m. Mus. Hist. Nat. 17: 115. 1828. 



Echinocactus coulteri Don, Hist. Dichl. PI. 3: 162. 1834. 



Echinocactus oxypterus Zucc. ; Pfeiff. Enum. Cact. 57. 1837. 



Echinocactus electracanthus Lem. Cact. Aliq. Nov. 24. 1838. 



Echinocactus lancifer Reichenb. ; Terscheck, Cat. Suppl. 2. 



Eastern Mexico. 



Simple, cs'lindric, 50 to 60 cm. in diameter, bluish green ; ribs about 24 ; 

 areoles 2 to 3 cm. apart; spines usually 10 to 12, a little curved, yellow, 

 becoming brown, of these 6 to 8 slender-subulate, 2 to 3 cm. long, more or less 

 spreading, 3 or 4 spines more central than the others, but usually only one 

 definitely so, much stouter and longer, 4 to 6 cm. long, porrect or ascending, 

 annulate ; flowers 2.5 to 3.5 cm. long, bright yellow, sometimes reddish with- 

 out ; inner perianth segments linear-oblong, acute, somewhat spreading ; scales 

 on the ovary ovate, acute, small, 2 to 4 mm. long, somewhat ciliate; fruit 

 short-oblong, about 2 cm. long, somewhat edible; seeds minute, 1 mm. long, 

 brown. " Biznaga costillona " (Durango, Pafom). 



22. Ferocactus macrodiscus (Mai't.) Britt. & Rose, Cactaceae 3: 139. 1922. 

 Echinocactus macrodiscus Mart. Nov. Act. Nat. Cur. 16: 341. 1832. 



San Luis Potosi and southward. 



Simple, depressed-globose or sometimes short-cylindric, sometimes 45 cm. 

 in diameter ; ribs 16, perhaps more in some specimens, somewhat flattened, 

 sometimes acute, somewhat depressed at the distant areoles; spines all yel- 

 low, more or less curved backward; radial spines 6 to 8, mostly 2 to 3 cm. 

 'long; central spines 4, stouter and flatter than the radials, 3.5 cm. long; 

 flowers 5 cm. long, dark red to purple, obconic ; inner perianth segments linear- 

 oblong, acute. 



23. Ferocactus viridescens (Torr. & Gray) Britt. & Rose, Cactaceae 3: 140. 

 1922. 



Echinocactus viridescens Torr. & Gray, Fl. N. Amer. 1: 554. 1840. 



Echinocactus limitus Engelm. ; Coulter, Contr. U. S. Nat. Herb. 3: 374. 1896. 



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



At first nearly globose or somewhat depressed, in age becoming cylindric, 30 to 

 45 cm. high, 25 to 35 cm. in diameter, simple or cespitose, deep green, somewhat 

 glossy; ribs 13 to 21, somewhat rounded, 1 to 2 cm. high, obtuse, undulate; 

 areoles narrow, elliptic, 1 to 2 cm. long, spine-bearing in the lower part, felted 

 in upper part, flower-bearing and also with several reddish glands, these 

 becoming elongate and spinescent in age; spines at first bright red, becoming 

 ■duller by age or turning yellow or horn-colored ; radial spines 9 to 20, more or 

 less spreading, 1 to 2 cm. long ; central spines 4, the lower one stouter and 

 more flattened, up to 3.5 cm. long; flowers yellowish green, 4 cm. long; 

 perianth segments oblong, obtuse, sometimes apiculate, more or less serrulate; 

 scales on the ovary orbicular, imbricate ; fruit 1.6 to 2 cm. long, reddish, with a 

 pleasant acid taste ; seeds 1.6 mm. long, pitted. 



24. Ferocactus nobilis (L.) Britt. & Rose, Cactaceae 3: 141. 1922. 

 Cactus nobilis L. Mant. PI. 243. 1767. 



Cactus recurvus Mill. Gard. Diet. ed. 8. Cactus no. 3. 1768. 



Echinocactus recurvus Link & Otto, Wochenschr. Ver. Bef(5rd. Gartenb. 3: 



pi. 20. 1827. 

 Echinocactus spiralis, Karw. ; Pfeiff. Enum. Cact. 60. 1837. 



