CONTENTS ix 



CHAPTER PAGE 



(IV) I. Commensalisra and saprophytism 752 



2. Parasitism 761 



Fungi and bacteria 762 



Seed plants 769 



Grafting 776 



Galls 780 



Autoparasitism . . . . . . . . 786 



3. Reciprocal parasitism, helotism, and endosaprophytism . . 786 



Root tubercles and their bacteria ...... 787 



Mycosymbiosis 791 



Lichens ........... 800 



Green-celled animals 803 



Reproduction and dispersal ......... 805 



1. Reproductive behavior in seedless plants 805 



Vegetative reproduction ........ 805 



/ Asexual reproduction 809 



Sexual reproduction 816 



2. Flowers 825 



Role 829 



tWind pollination 834 



JWater pollination ......... 838 



Unsect pollination 838 



Geitonogamy 862 



Autogamy ........... 863 



Protective features 869 



Origin of floral structures 875 



3. Influence of external factors upon reproductive organs . ^ . 878 



Seedless plants 878 



Origin of sexuality ........ 881 



Artificial parthenogenesis . . . . . . . 882 



Sexuality in the fungi . . . . . . . . . 883 



Bryophytes and pteridophytes 884 



Seed plants 885 



Vegetative and reproductive periods ..... 885 



Sex determination 895 



Flower color ......... 898 



Size and number of floral organs 900 



Flower form 9 



Hybridization 94 



Bud variation 94 



4. Fruits and seeds 94 



Protective structures ..... 96 



Food accumulation 9 11 



Variation in relation to external factors 9 f 6 



Dehiscence 9 f 9 



Dispersal 9*9 



Origin of seed structures 9 2 8 



Planting of seeds 9 2 8 



VI. Germination ..... 93 



Vivipary -93 



