STANDLEY TEEES AND SHRUBS OF MEXICO. 963 



Stems ascending, 30 cm. high ; tubercles short, their axils woolly but not 

 setose; radial spines 10 to 12, white Avith black tips, widely spreading, un- 

 equal, 10 to 34 mm. long, slender; central spines 1 to 4, stouter than the radials, 

 one of them strongly hooked ; fruit obovoid, 3 cm. long, scarlet ; seeds black 

 and pitted. 



4. Cochemiea pondii (Greene) Walton, Cact. Journ. 2: 51. 1S99. 



Mammillaria pondii Greene, Pittonia 1: 268. 1889. 



Islands off the west coast of northern Baja California ; type from Cedros 

 Island. 



Stems at first upright, cylindric, simple or few-branched, 7 to 30 cm. high, 

 hidden under a dense covering of spines ; axils of tubercles setose ; young 

 areoles white-tomentose ; radial spines white or whitish or sometimes brownish, 

 15 to 25, spreading; central spines 8 to 11, much longer and stouter than the 

 radials, the longest 3 cm. long, 1 or 2 hooked ; flowers slender, 5 cm. long, 

 bright scarlet ; fruit purplish red, 18 mm. long, ovoid to obovoid. 



44. CORYPHANTHA Lem. Cact. 32. 1868. 



Plant body globular to cylindric, either simple or cespitose ; tubercles, ex- 

 cept the very earliest ones, grooved on the upper surface from apex to base; 

 flowers from near the top of the plant and from the base of young and 

 growing tubercles, large and showy, generally yellow, sometimes purple or 

 red ; ovary naked or bearing a few scales in some species ; perianth long- 

 persistent ; fruit large, ripening slowly, ovoid to oblong, greenish or yellow- 

 ish ; seeds brown, lightly reticulate or nearly smooth. 



A few other species occur in the United States, and one is found in Cuba. 



Tubercles grooved to middle or a little below; ovary bearing scales with 

 woolly axils. 



Tubercles elongate, bright green 1. C. macromeris. 



Tubercles short, grayish green 2. C. runyonii. 



Tubercles grooved from tip to base; ovary naked. 



Grooves of tubercles bearing large yellow or red glands. 



Flowers white 3. C. ottonis. 



Flowers not white. 

 Stems globular. 



Radial spines more or less recurved 4. C. recurvata. 



Radial spines spreading or ascending. 



Spines dark, sometimes black— 5. C. poselg'eriana. 



Spines yellow or sometimes tinged with red. 



Central spines slender and flexible 6. C. mueWenpfordtii. 



Central spines stout and rigid. 



Radial spines subulate 7. C. guerkeana. 



Radinl spines acicular 8. C. echinoidea. 



Stems cylindric. 



Stems bluish green 9. C. clava. 



Stems yellowish green. 

 Central spine generally one. 



Glands in groove red 10. C. octacantha. 



Glands in groove yellow 11. C. exsudans. 



Central spines 2 12. C. erecta. 



Grooves of tubercles without large glands. 

 Outer perianth segments not ciliate. 

 Flowers purplish or rose 13. C. elephantidens. 



