STANDLEY — TEEES AND SHRUBS OF MEXICO. 953 



with a dense felty mass; upper scales narrow, rigid, more or less spiny- 

 tipped; outer perianth segments ovate, long-apiculate, with ciliate margins; 

 inner segments oblong, obtuse, retuse or apiculate, serrulate; fruit hidden in 

 a mass of soft white wool, oblong, 4 to 5 cm. long ; seeds black, shining, 2.5 

 mm. long. 



5. Echlnocactus platyacanthus Link & Otto, Woclienschr. Ver. Beford. 



Gartenb. 3:423.1827. 



Eastern Mexico. 



Stems nearly globular, 50 cm. high, 60 cm. broad, light green, very woolly 

 at apex ; ribs 21 to 30. acute ; spines brownish at first, grayish in age ; 

 radial spines 4, spreading. 12 to 10 mm. long; central spines 3 or 4, spread- 

 ing, 3 cm. long; flowers 3 cm. long, long-woolly; outer perianth segments 

 lanceolate, mucronate ; inner perianth segments obtuse, yellow. 



6. Echinocactus palmeri Rose, Contr. U. S. Nat. Herb. 12: 299. 1909. 

 Coahuila to Zacatecas; type from Concepcion del Rio, Zacatecas. 



Stems 1 to 2 meters high, 40 to 50 cm. in diameter; ribs 12 to 26, or per- 

 haps more in large plants ; central spines 4, annular, the upper one erect, 

 (5 to 8 cm. long, stout, straight, j'ellow above, brownish and somewhat 

 swollen at base, the 3 lower ones shorter, spreading, similar in color and 

 markings but flattened ; radial spines 5 to 8, much smaller, lighter colored 

 and weaker ; flowers yellow, rather small ; perianth segments about 2 cm. long, 

 more or less lacerate along the margin ; fruit about 3 cm. long, hidden in a 

 dense covering of soft white wool ; scales weak and bristle-tipped. " Biznaga 

 burra " (Zacatecas). 



7. Echinocactus polycephalus Engelm. & Bigel. Proc. Amer. Acad. 3: 276. 1856. 

 Northern Sonora ; reported from Baja California. Utah and Arizona to 



California ; type from the Mojave River, California. 



Solitary when young, in age forming large clumps of 20 to 30 heads, each 

 globular to short-cylindric, sometimes as much as 70 cm. high but usually 

 smaller ; ribs 13 to 21, rather stout, 2 to 3 cm. high, somewhat undulate, nearly 

 hidden under the dense spine armament; areoles 10 to 12 ram. in diameter, 

 1 to 3.5 cm. apart ; spines 7 to 15, when young covered with a downy felt but 

 afterwards glabrate, reddish, subulate, more or less flattened, the radials 2.5 

 to 5 cm. long ; central spines 4, stouter than the radials, 3 to 9 cm. long, more 

 or less annulate ; flowers yellow, 5 to 6 cm. long ; scales on ovary minute, 

 hidden under the mass of long wool borne in their axils ; scales on flower 

 tube numerous, only a little longer than the wool, chartaceous, pungent ; inner 

 perianth segments linear-oblong, 2.5 to 3 cm. long, entire, obtuse ; fruit densely 

 woolly, crowned by the somewhat spinescent scales, globose to oblong, dry, 1.5 

 to 2.5 cm. long, dehiscing by a basal pore ; seeds angled, papillose, dull black, 3 

 to 4 mm. long. 



8. Echinocactus horizonthalonius Lem. Cact. Hort. Slonv. 19. 1839. 

 Echinocactus equitans Scheidw. Bull. Acad. Brux. 6^: 88. 1839. 

 Echinocactus laticostatus Engelm. & Bigel. U. S. Rep. Expl. Miss. Pacif. 4: 



32. 1856. 



Northern Mexico. Western Texas to Arizona. 



Simple, globular or sometimes depressed or short-cylindric, 4 to 25 cm. high, 

 glaucous ; ribs 7 to 13, obtuse, often spirally arranged ; spines 6 to 9, some- 

 what curved or straight, 2 to 4 cm. long, often very stout, more or less flat- 

 tened, often annulate, reddish or sometimes blackish at base; central spine 

 solitary, stouter than the radials ; flowers pale rose to pink, 5 to 7 cm. long 

 before expanding, broader than long when fully open ; outer perianth seg- 



