The Morphology of Ruppia Maritima. 63 



PAGES 



ECOLOGY or THE VEGETATIVE ORGANS . . . .115 



Introductory 115 



Hydrophytic Adaptations ......... 116 



A. The Shoot 116 



1. Gross Morpliological Aaaptatioiis . . . . . 116 



2. Internal Structural Adaptations 117 



a. Epidermal Modifications 117 



b. Development of Air Spaces ...... 118 



c. Absence of Mechanical Tissue . . . . . 119 



d. Reduction of the Vascular System .... 119 



B. The Root 120 



1. Gross Morphological Adaptations 120 



2. Internal Structural Adaptations ..... 121 



a. Air Spaces 121 



b. Reduction of the Vascular System .... 121 

 Halophytic Adaptations 121 



A. General 121 



B. The Adaptation to a Salt Water Envii*onment . . . 122 



Adaptation and Heredity 126 



Summary 126 



REPRODUCTIVE ORGANS 128 



Morphology of the Flower . . . 128 



Eloral Development 130 



Microsporangium 131 



Megasporangium 185 



Eemale Gametophyte 136 



Male Gametophyte . 139 



Pollination 143 



Eertilization 144 



Endosperm 145 



EMBRYO 146 



FRUIT AND SEED 156 



SEEDLING 158 



SUMMARY OF PARTS ON REPRODUCTIVE ORGANS, EM- 

 BRYO, &c 160 



SUMMARY OF RELATIONSHIPS TO OTHER POTAMOGETON- 



ACEAE 162 



BIBLIOGRAPHY 165 



EXPLANATION OF PLATES 170 



