CONTENTS 



Page 



Dependent nutrition in seed-plants 1 



The root habits and parasitism of Krameria canescens 5 



Parasitic seed-plants of the desert 5 



Krameria canescens and some features of the Kramerias 5 



Root-system of Krameria canescens 6 



Anatomy of the roots 8 



The haustorium 8 



Krameria and its hosts 10 



Acacia constricta 10 



Covillea tridentata H 



E ncelia f ari nosa 13 



Ephedra antisyphilitica 15 



Franseria dumosa 16 



Lycium andersonii 16 



Menodora scabra 17 



Parkinsonia microphylla 17 



Prosopis velutina 18 



Zizyphus parry i 19 



Cultures of Krameria canescens 20 



Summarization of general features of parasitism of Krameria L'l 



Xeno-parasitism: the experimental induction of dependent nutrition 25 



Material and methods 25 



Total and inorganic solids 25 



Determination of acidity 26 



C issus-Opun tia -7 



Cissus-Echinocactus 31 



Cissus-Carnegiea 'M 



Cissus-Fouquieria 36 



Opuntia-Echinocactus '!<> 



Autonomic movements of Opuntia 37 



Opuntia-Opuntia 42 



Opuntia-Fouquieria 4l* 



Opuntia-Carnegiea 42 



Euphorbia-Opuntia 44 



Fouquieria-Opuntia, Fouquieria-Carnegiea, and Fouquieria-Echinocactus.... 4."> 



Cotyledon-Opuntia 45 



Cotyledon-Carnegiea > 45 



Cotyledon-Echinocactus 45 



Agave-Echinocactus 45 



Agave-Opuntia 46 



Agave-Carnegiea 47 



Tradescantia-Opuntia 48 



Miscellaneous arrangements 48 



Resume of experimental results 48 



The origination of parasitism 50 



iii 



