INHERITANCE OF HABIT IN THE COMMON BEAN 



JOHN B. NORTON, M.S. 

 Massachusktts KxPKKiaiKXT Station 



Habit is the external form of a plant taken as a whole. 

 It is usually described by a few general adjectives, such 

 as erect, open, spreading, etc. However, to study the 

 inheritance of plant habit, a detailed analysis of the real 

 characters underlying habit must be made. It is usually 

 found that the general outer appearance of a plant, its 

 habit, is the result of a combination of independent char- 

 acters, units, the recombination of which by crossing 

 often results in plants much altered in appearance from 

 the parent varieties. Characters usually unimportant 

 may be found of primary importance in the formation of 

 plant habit. 



An example of such inheritance of habit is found in one 

 of Webber's pepper hybrids (6). A cross was made be- 

 tween Red Chili, a variety with many erect line branches, 

 and Golden Dawn, with few, horizontal, coarse branches, 

 both being of medium size. In the second generation re- 

 combination and segregation of the three character pairs 

 occurred, although not in strict Mendelian proportions. 

 The important feature of the results, however, lies in the 

 apparent creation of a giant and a dwarf type, not by the 

 appearance of new units by mutation, but simply by the 

 transference of the characters fine and coarse branches. 

 Hybrids having erect, many and coarse branches were 

 giants, while those having few, horizontal and coarse 

 branches were dwarfs. Other combinations of these 

 characters gave intermediate forms. 



The study here reported was made largely on third and 

 fourth generation plants and a few second generation 

 plants of hybrids made primarily for the study of pig- 

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