4 THE CACTACEAE. 



In habit it simulates the South American genus, Echinopsis, while in flowers and fruits 

 it comes near Erdisia, Bergcrocactus, and Wilcoxia. While all the species are low in habit 

 there is great variation in the manner and form of growth. Some are solitary; others grow 

 in flat masses, and others in large rounded mounds. The flowers, while always having 

 a spiny ovary and flower-tube and green stigma-lobes, have considerable variation in 

 the shape and color of perianth-segments and in duration. The flower-buds as well as 

 the young shoots are deep-seated in their origin and do not appear just at the areoles as 

 in most cacti and hence must break through the epidermis when they develop. A some- 

 what similar result is produced in the flowering of some of the species of Rhipsalis. Echino- 

 cereus has been selected as the state flower of New Mexico. 



Most plants of Echinocercus do not flower frequently in greenhouse cultivation. 



The species are not readily grouped into series; our classification of them is largely 

 artificial, taking flower-color as a more important character than it probably is in nature. 



Key to Species. 



A. Flowers large, usually conspicuous, rarely only 2 to 3 cm. long. 



B. Stems covered with long weak bristles or hairs, resembling a small plant of Ceph- 



alocereus senilis 1. E. delaetii 



BB. Stems variously covered with spines or rarely spineless, never like the above. 



C. Flowers scarlet to salmon-colored, opening once, but lasting for several days. 



Stems usually weak, often trailing, or at least becoming prostrate; ribs nearly con- 

 tinuous. 



Flowers rosy red 2. E. scheeri 



Flowers orange-red to salmon-colored. 



Flowers 8 to 1 1 cm. long; wool from areoles on flower- tube long. 



Flowers 8 to 10 cm. long; radial spines 9 or fewer 3. E. salm-dyckianus 



Flowers 1 1 cm. long; radial spines 10 to 12 4. E. huitcholensis 



Flowers 6 cm. long or less; wool from areoles on flowers shorter than subtending 



scale 5. E. pensilis 



Stems usually erect and stout; ribs more or less tubercled. 



Plants forming large mounds, sometimes with 500 to 800 joints; spines white, long 



and flexuous 6. E. mojavensis 



Plants in much smaller clusters; spines brownish or grayish, not long and flexuous. 



Plant body with 12 to 14 ribs 7. E. leeanus 



Plant body with 5 to n ribs (in one species 12). 



Ribs 5 to 8 8. E. triglochidiatus 



Ribs 9 to 12. 



Axils of flower-scales filled with long cobwebby hairs. 



Flowers 5 to 6 cm. long; spines yellowish at first 9. E. polyaeanthus 



Flowers 3 cm. long; spines reddish at first 10. E. pacificus 



Axils of flower-scales bearing short hairs. 



Stems elongated and thinner than in E. oclacanthus 11. E. acifer 



Stems short and thicker than in E. acifer. 



Stems pure green when old; central spine 1 12. E. oclacanthus 



Stems bluish green; central spines several. 



Central spines 6; petals acutish 13. E. neo-mexicanus 



Central spines mostly 4, sometimes 3 or 5. 



Central spines more or less angled, somewhat curved 14. E. conoideus 



Central spines terete, straight. 



Central spines white or straw-colored 15. E. coccineus 



Central spines gray to pinkish 16. E. rosei 



CC. Flowers broad, rotate to campanulate, opening in sunlight, closing at night, usually 

 purple, sometimes yellow or greenish yellow, rarely pink or 

 nearly white, unknown in E. standleyi. 

 D. Flowers yellow or greenish white. 

 Ribs not strongly tubercled. 



Plants densely cespitose 17. E. maritimus 



Plants usually solitary. 

 Ribs very stout. 



Ribs 5 to 8; spines on flower-tube and ovary short 18. E. suhinermis 



Ribs 8 or 9; spines on flower-tube and ovary acicular 19. E. luleus 



Ribs low, usually hidden by the spines. 

 Flowers small, 2.5 cm. long or less. 



Areoles circular 20. E. chloranlhus 



Areoles elliptic 21. E. viridiflorus 



Flowers large, 5 to 10 cm. long. 



Flowers greenish white 22. E. grandis 



Flowers yellow-red. 



