A Comparative Study of the Structure and 



Saprophytism of the Pyrolaceae and 



Monotropaceae with Reference 



to their Derivation from 



the Ericaceae 



Margaret W. Henderson, B.S., M.A. 



[Thesis presented to the Faculty of the Graduate School in partial fulfillment of the 

 Requirements for the Degree of Doctor of Philosophy.] 



CONTENTS 



PAGE 



Introduction 43 



Historical 48 



Methods and Materials Used 5° 



The Underground Root and Stem Systems 51 



The Root 53 



The Rhizome 64 



The Ascending Axis 64 



The Leaf 75 



The Leaf — Microscopic Structure 78 



The Inflorescence 87 



The Sepals 90 



The Petals 92 



The Stamens 94 



The Pistil 97 



The Fruit and Seed 10 1 



Summary 103 



Conclusions 105 



Bibliography 106 



42 



