CONTENTS. 



PAGE. 



Introduction 3 



Order Cactales 8 



Family Cactaceae 8 



Key to Tribes 8 



Tribe Pereskieae 8 



Pereskia 8 



Key to Species 9 



Tribe Opuntieae 24 



Key to Genera 24 



Pereskiopsis 25 



Pterocactus 30 



Nopalea 33 



Tacinga 39 



Maihuenia 40 



Opuntia 42 



Key to Subgenera and Series 44 



Subgenus Cylindropuntia 46 



Series Ramosissimae 46 



Series Leptocaules 46 



Series Thurberianae 52 



Series Echinocarpae 56 



Series Bigelovianae 58 



Series Imbricatae 60 



Series Fulgidae 67 



Series Vestitae 71 



Series Clavarioides 72 



Series Salmianae 73 



Series Subulatae 75 



Series Miquelianae 78 



Series Clavatae 79 



Subgenus Tephrocactus 84 



Series Weberianae ■. 84 



Series Floccosae 86 



Series Glomeratae 87 



Series Pentlandianae 90 



PAGB. 



Family Cactaceae — continued. 

 Tribe Opuntieae — continued. 

 Opuntia — continued. 



Subgenus Platyopuntia 99 



Series Pumilae 100 



Series Curassavicae 102 



Series Aurantiacae 106 



Series Tunae no 



Series Basilares 118 



Series Inamoenae 125 



Series Tortispinae 126 



Series Sulphureae 133 



Series Strigiles 136 



Series Setispinae 136 



Series Phaeacanthae 139 



Series Elatiores 149 



Series Elatae 156 



Series Scheerianae 159 



Series Dillenianae 159 



.Series Macdougalianae 169 



Series Tomentosae 172 



Series Leucotrichae 1 74 



Series Orbiculatae 1 76 



Series Ficus-indicae 177 



Series Streptacanthae 181 



Series Robustae 191 



Series Poly acanthae 193 



Series Stenopetalae 200 



Series Palmadorae 201 



Series Spinosissimae 202 



Series Brasilienses 209 



Series Ammophilae 211 



Series Chaffeyanae 213 



Grusonia 215 



Appendix 216 



Index : . . . 227 



