the; cactaceae. 



Key to Genera — continued. 



CC. Ovary squamiferous, often also laniferous, setiferous, or spiniferous. 



Flowers in a large lateral pseudocephalium; columnar cacti 4. Espostoa (p. 60) 



Plants without a pseudocephalium. 



Ovary squamiferous onty; columnar cacti. 

 Scales of the ovary fleshy. 



Flower short-funnelf orm ; scales of ovary and flower-tube acute 5. Browningia (p. 63) 



Flower long-f unnelform ; scales of ovary and flower-tube broad, 



abruptly cuspidate 6. Stetsonia (p. 64) 



Scales of the ovary papery 7. Escontria (p. 65) 



Ovary squamiferous and also laniferous, felted, or spiniferous. 



Perianth short-campanulate or short-funnelform, its tube short or thick. 

 Plants mostly stout, columnar, and erect, ribbed or angled; a few 

 species spreading or prostrate; rootstocks not tuberous. 

 Corolla short-campanulate. 



Corolla falling away by abscission, yellow; columnar cacti. ... 8. Corryocactus (p. 66) 

 Corolla withering-peristent; flowers not yellow. 



Fruit dry; columnar cacti 9. Pachycereus (p. 68) 



Fruit a fleshy berry. 



Tree-like, or bushy cacti 10. Leptocereus (p. 77) 



Columnar cacti 11. Eulychnia (p. 82) 



Corolla short-funnelform; fruit fleshy. 



Mostly columnar cacti with stout stems, the white to pink 



flowers not widely expanded 12. Lemaireocereus (p. 85) 



Slender or low cacti, with bright red, scarlet, or yellow, widely 

 expanded flowers. 



Branches slender, few to several-ribbed 13. Erdisia (p. 104) 



Branches stout, closely many-ribbed 14. Bergerocactus (p. 107) 



Stems very slender, nearly terete or with many low ribs. 



Inner perianth-segments much shorter than tube 15. Leocerens (p. 108) 



Inner perianth-segments as long as tube; rootstocks tuberous. . . 16. Wilcoxia (p. no) 

 Perianth funnelform, funnelform-campanulate, or salverform. 

 Areoles of the ovary spinuliferous or setiferous (see Harrisia). 



Slender cacti, with an enormous fleshy root ; flower salverform. . 17. Peniocereus (p. 112) 

 Stout or slender cacti, without a large fleshy root; flower funnel- 

 form. 

 Tree-like cacti ; fruit with a thick woody rind ; ovary few-spined .18. Dendrocereus (p. 113) 

 Prostrate or bushy or vine-like cacti ; fruit fleshy. 



Stout, bushy or prostrate cacti, the spines dagger-like, flat. . 19. Machaerocereus (p. 114) 

 Slender or weak cacti, the spines acicular or subulate. 



Perianth-tube as long as the limb or longer; elongated 

 cacti with white flowers. 

 Joints ribbed. 



Perianth-segments and filaments elongated 20. Nyctocereus (p. 117) 



Perianth-segments and filaments short 21. Brachycereus (p. 120) 



Joints angled 22. Acanthocereus (p. 121) 



Perianth-tube mostly shorter than the limb; bushy cacti 



usually with scarlet flowers 23. Heliocereus (p. 127) 



Areoles of the ovary laniferous or felted (also setiferous in some 

 species of Harrisia). 

 Perianth-limb regular. 



Perianth funnelform or salverform; tube mostly longer than 

 limb. 

 Stout, upright cacti, columnar or with columnar branches. 

 Perianth- tube bearing areoles to top; perianth-segments 



broad 24. Trichocereus (p. 130) 



Perianth- tube slender, with few areoles or none; perianth- 

 segments narrow 25. Jasminocereus (p. 146) 



Slender, arching, vine-like or bushy cacti. 



Arching or vine-like cacti 26. Harrisia (p. 147) 



Low, bushy cacti 27. Borzicactus (p. 159) 



Perianth funnelform-campanulate, the tube stout. 



Gigantic, columnar cacti; scales of flower broad 28. Camegiea (p. 164) 



Stout, bushy cacti; scales of flower narrow 29. Binghamia (p. 167) 



Perianth-limb oblique; erect or bushy cacti with scarlet flowers. .30. Rathbunia (p. 169) 

 Perianth subcylindric, the limb short or none. 



Scales when present on the ovary and flower- tube naked in their axils 31. Arrojadoa (p. 170) 



Scales on the ovary and flower-tube laniferous in their axils. 

 Flowers borne from a lateral pseudocephalium. 



Flower-tube elongated; fruit dry 32. Oreocereus (p. 171) 



Flower-tube very short; fruit not dry 33- Facheiroa (p. 173) 



Flowers not borne from a lateral pseudocephalium. 



Perianth-tube elongated, slender; stamens exserted 34- Ckistocactus (p. 173) 



Perianth-tube very short; stamens included 35- Zehntnerella (p. 176) 



