HEREDITY STUDIES IN THE MORNING-GLORY (IPOMOEA 



PURPUREA [L.] ROTH)i 



Elmer Eugene Barker 



It is attempted in this paper to give the results obtained in researches 

 on the genetics of certain characters in the common morning-glory 

 (Ipomoea purpurea [L.] Roth), and to demonstrate the mendelian behavior 

 of certain genes postulated to explain them. The characters here studied 

 are color of the seed coat, and feathering, color, and flaking of the corolla. 



The morning-glory is a plant well suited for work in experimental 

 genetics. Its flowers present a large series of color types; it is vigorous, 

 and very resistant to adverse conditions of all sorts; it is self-fertile and 

 bears many seeds on every plant ; it is very resistant to most insect attacks 

 and fungous diseases; it can be grown in the greenhouse as well as out 

 of doors if the temperature is warm enough. 



METHODS USED IN STUDY 



The stock used was the common variety of morning-glory. At the 

 beginning of the investigation some Japanese morning-glories were grown, 

 but they proved to be tender under the very cool conditions that prevailed 

 in the house where they were planted, and no crosses were obtained, either 

 between the two kinds or between the Japanese varieties themselves. 



If the house is cool or the light is insufficient (as during winter months 

 at Ithaca), the plants will not vine and will bloom as soon as one or two 

 pairs of true leaves have unfolded. If the temperature is warm and 

 htmiid, or under optimum garden conditions, the vines become very 

 largfe and do not bloom until late. In these experiments a con^'enient 

 medium was struck by growing the plants in small pots, whereby they 

 could- be kept at small size but still large enough to produce plenty of 

 flowers. 



At first the seeds were sown in the small pots, one to a pot, and the pots 

 were plunged 'into the soil or ashes of the greenhouse bench or of the 

 garden. It was found better to germinate the seeds between damp blotters 

 in a germinator and then to plant the young seedlings. In the spring of 

 19 1 5 an attempt to germinate the seeds in damp cotton proved disastrous, 

 because they smothered and more than half of the cultures were thus lost. 

 Some of the seeds have integuments so impervious to moisture that germi- 

 nation is very slow under natural conditions. It can be hastened by 



1 Paper No. 60, Department of Plant Breeding, Cornell University, Ithaca, New York. 



121 



