Chapter Fourteen 



BALANCE OF ROOT AND SHOOT 



Interdependence of root and shoot for food and water (92). Carbon 

 and nitrogen ratio (93). Pruning and the nitrogen balance (94). 

 Transplanting (95). 



Chapter Fifteen 



INSECTS AND DISEASES 



The problem (97). The epidermis as a protection against insects and 

 diseases (98). How diseases spread (98). Spraying to kill insects 

 according to the way they injure the plant ( 101 ). Contact and stomach 

 poisons (101). 



Chapter Sixteen 



WEEDS 



Competition of weeds and desired plants ( 104). Annuals, biennials and 

 perennials (104). Weed seed germination (106). Weeds propagated 

 by stem or root cuttings (107). Weeds in the lawn (108). KilHng 

 weeds with chemicals (111). 



Chapter Seventeen 



FLOWERS 



Described (112). Parts of the flower (115). The stamen (116). The 

 pistil (116). The clover type (117). The sunflower type (118). The 

 grass type (118). The pollen (118). Pollination (119). FertiHza- 

 tion(119). Xenia(120). Metaxenia (120). 



Chapter Eighteen 



HYBRIDIZING PLANTS 



Illustrations (122). The work of Mendel (123). His seven experi- 

 ments (125). Mendel's second law (129). Reduction division (131), 

 Work of Burbank (137). Methods of hybridizing for the gardener 

 (138). Hybrids (139). 



Chapter Nineteen 



HEREDITY AND VARIATION IN PLANTS 



Progress of early peoples (141). Heredity and variation (142). How 

 employed by plant breeders (143). Mutations (143). Selection and 

 pure lines (145). Methods of increasing the number of mutations 

 (146). Colchicine (147). Examples of plant improvement (148). 



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