ILLUSTRATIONS. 



PLATES. P ^£ G 



Plate i. Group of plants of Cephalocereus macrocephalus on hillside near Tehuacan Frontispiece. 



Plate 2. (1) Top of flowering stem of Cereus alacriportanus. (2) Top of stem of Cereus peruvianus. 



(3) Flower of Cereus peruvianus 6 



Plate 3. (1) Top of stem of Cereus validus. ■ (2) Top of flowering stem of Cereus validus. (3) Top of flow- 

 ering branch of Monvillea cavendishii. (4) Top of branch of M. cavendishii, with fruit. 22 

 Plate 4. (1) Flowering stem of Cephalocereus pentaedrophorus. (2) Top of stem of Cephalocereus gounel- 

 lei. (3) Top of stem of Cephalocereus bahamensis, with flower. (4) Fruit of Cepha- 

 locereus deeringii 32 



Plate 5. A clump of plants of Cephalocereus deeringii on Lower Matecumbe Key, Florida 38 



Plate 6. (1) Top of flowering stem of Cephalocereus arrabidae. (2) Top of flowering stem of Cephalo- 

 cereus nobilis. (3) Top of flowering stem of Cephalocereus barbadensis 42 



Plate 7. (1) Plants of Cephalocereus polygonus. (2) Large plant of Cephalocereus chrysacanthus 48 



Plate 8. (1) Top of flowering stem of Cephalocereus brooksianus. (2) Top of stem of Cephalocereus ca- 

 tingicola. (3) Top of stem of Cephalocereus phaeacanthus. (4) Flowering branch of 



Leptocereus assurgens 56 



Plate 9. A large plant of Stetsonia coryne in the desert of northern Argentina 64 



Plate 10. A plant of Escontria chiotilla, near Tehuac&n, Mexico 66 



Plate i'i. Top of flowering plant of Pachycereus chrysomallus 72 



Plate 12. A mountain-side along Tomellin Canyon, Mexico, covered with Pachycereus columna-trajani. ... 76 



Plate 13. (1) Top of flowering branch of Leptocereus arboreus. (2) Top of stem of Lemaireocereus griseus. 



(3) Fruiting branch of Mediocactus coccineus 80 



Plate 14. (1) Part of branch of Dendrocereus nudiflorus. (2) Flowering branch of Dendrocereus nudiflorus. 



(3) Flowering branch of Nyctocereus guatemalensis 1 14 



Plate 15. (1) Top of branch of Eulychnia iquiquensis. (2) Top of stem of Lemaireocereus dumortieri. 



(3) Part of flowering stem of Nyctocereus serpentinus 118 



Plate 16. (1) Top of flowering branch of Acanthocereus pentagonus. (2) Top of flowering branch of Acan- 



thocereus subinermis. (3) Top of a fruiting branch of Acanthocereus subinermis. ... 124 

 Plate 17. (1) End of flowering branch of Heliocereus elegantissimus. (2) End of flowering branch of Helio- 



cereus speciosus. (3) A tip of a fruiting branch of Harrisia portoricensis 128 



Plate 18. (1) Tip of a flowering branch of Harrisia eriophora. (2) Fruiting branch of Harrisia eriophora. . 148 

 Plate 19- (1) Top of flowering branch of Harrisia fragrans. (2) Top of fruiting joint of Harrisia fragrans. 



(3) Fruiting branch of Harrisia martinii 150 



Plate 20. (1) Part of fruiting branch of Harrisia gracilis. (2) Top of flowering branch of Harrisia martinii. 152 



Plate 21. (1) Flowering branch of Harrisia tortuosa. (2) Fruiting branch of Harrisia tortuosa 156 



Plate 22. Top of flowering plant of Carnegiea gigantea 164 



Plate 23. The giant cactus, Carnegiea gigantea, near Tucson, Arizona 166 



Plate 24. (1) Top of flowering branch of Harrisia fernowi. (2) Flowering branch of Harrisia bonplandii. 



(3) Top of branch of Binghamia melanostele 168 



Plate 25. (1) Flowering branch of Rathbunia alamosensis. (2) Flowering branch of Rathbunia alamosensis. 

 (3) Top of flowering branch of Borzicactus acanthurus. (4) Top of stem of Arrojadoa 



rhodantha 170 



Plate 26. d) Myrtillocactus geometrizans, Tehuacan, Mexico. (2) Myrtillocactus schenckii, near Mitla, 



Mexico 180 



Plate 27. (1) End of fruiting branch of Arrojadoa rhodantha. (2) Top of plant of Cleistocactus baumannii. 



(3) Flower on branch of Hylocereus stenopterus 184 



Plate 28. Flower on end of branch of Hylocereus ocamponis 186 



Plate 29. Flower on end of branch of Hylocereus monacanthus 188 



Plate 3°- Flower near end of branch of Hylocereus undatus 190 



Plate 31- Flower on short branch of Hylocereus lemairei 192 



Plate 32. (1) Fruit of Hylocereus undatus. (2) Flowering branch of Wilmattea minuciflora. (3) Longitu- 

 dinal section of fruit of Selenicereus grandiflorus 196 



Plate 33. (1) Flowering branch of Selenicereus grandiflorus. (2) Tip of branch of Selenicereus grandi- 

 florus. (3) Fruit of Selenicereus grandiflorus 198 



Plate 34. Flowering branch of Selenicereus urbanianus 200 



Plate 35. Flower on branch of Selenicereus coniflorus 202 



Plate 36. (1) Fruit of Hylocereus trigonus. (2) Flower of Selenicereus boeckmaunii. (3) Fruit of Seleni- 

 cereus boeckmannii 204 



Plate 37. Flower of Mediocactus coccineus 212 



Plate 38. (1) Fruiting branch of Selenicereus pteranthus. (2) Flowering branch of Selenicereus spinulosus. 



(3) Flowering branch of Weberocereus panamensis : 214 



Plate 39- (1) Flowering branch of Weberocereus tunilla. (2) Flowering branch of Weberocereus biolleyi. 



(3) Flowering branch of Werckleocreeus tonduzii. (4) Flower of Werckleocereus glaber. 216 

 Plate 4o. (i) Flowering plant of Aporocactus leptophis. (2) Flowering plant of A. flagelliformis 218 



IV 



