856 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Areoles mostly spine-bearing ; plants often not jointed, the joints not flat ; 

 plants terrestrial. 

 A. Flowers and spines borne at the same areoles. 

 B. Plants several-jointed or many-jointed, the joints elongate. 

 Plants vinelike, with aerial roots. 

 Ovary and fruit covered with large foliaceous scales, the axils 

 neither spiny, hairy, nor bristly. Stems and branches 3- 



angled or 3-winged 21. HYLOCEREITS. 



Ovary and fruit not bearing large foliaceous scales, the axils 

 spiny, hairy, or bristly. 

 P'lowers elongate-funnelform. 



Stems ribbed, fluted, or angled 22. SELENICEBEUS. 



Stems winged 23. DEAMIA. 



Flowers short-funnelform 24. APOROCATUS. 



l^ hints erect, treelike, bushy, arching, or diffuse. 

 Flowers 2 to several at an areole, small. 

 Flowering areoles bearing many long bristles. 



19. LOPHOCEREUS. 

 Flowering areoles without bristles-_20. MYRTILLGCACTITS. 

 Flowers solitary at the areoles, mostly large. 

 Ovary naked or rarely bearing a few short scales, these some- 

 times subtending tufts of short hairs. 



6. CEPHALOCEREUS. 

 Ovary with scales, often bearing also wool, bristles, or spines. 



Ovary with scales only 7. ESCONTRIA. 



Ovary with scales and also with wool, felt, or spines. 

 Perianth short-campanulate or short-funnelform, its tube 

 short and thick. 

 Plants mostly stout, columnar, and erect, ribbed or an- 

 gled ; roots without tubers. 

 CJoroUa short-campanulate; fruit dry. 



8. PACHYCEREUS. 

 Corolla short-funnelform ; fruit fleshy. 



Plants columnar, with stout stems ; flowers white to 

 pink, not widely expanded. 



9. LEMAIREOCEREUS. 

 Plants low; flowers pale yellow. 



10. BERGEROCACTUS. 

 Plants very slender, nearly terete or with many low 



ribs; roots with tubers 11. WILCOXIA. 



Perianth funnelform, fimnelform-campanulate, or salver- 

 form. 

 Areoles of the ovary with spines or bristles. 

 Plants slender, with a large fleshy root ; flowers 



salverform 12. PENIOCERETJS. 



Plants stout or slender, without large fleshy roots ; 

 flowers funnelform. 

 Plants stout, bushy or prostrate, the spines flat. 



dagger-like 13. MACHAEROCEREUS. 



Plants slender or weak, the spines acicular or 

 subulate. 



