Folsom: Potato Alutants 



47 



PARTLY REVERTED 



Figure 21. This plant was raised from a tuber of the simple-leaved plant shown in 

 Figure 20. Two of its leaves were half simple and half compound, but the plants raised 

 from it were all simple-leaved. The fact that these plants ipartly revert to the normal after 

 two generations of abnormality precludes the possibility of their unusual leaves being due to 

 "degeneration disease." From this there is no recovery as long as vegetative propagation is 

 continued. 



a clonal variety, and have been un- 

 stable enough to revert in part to the 

 varietal norm. The five cases to be 

 described were the only ones noticed in 

 over 350,000 plants observed for foli- 

 age diseases. 



A simple-leaf sport of the Green 

 Mountain variety canie under the 

 writer's observation in northeastern 

 Maine in 1920 as a single hill in a 

 commercial field. The second, third 



*The generations referred to in this paper 

 tions. — Editor. 



and fourth generations* were grown 

 respectively in the greenhouse at Orono 

 the following winter (Fig. 20), in the 

 field in the summer of 1921, and in 

 the field in 1922. The third generation 

 (consisting of a one-stalked plant) ap- 

 parently reverted partly to a compound- 

 leaf condition, two leaves being divided 

 longitudinally so that each was half 

 simple-leaf and half compound-leaf 

 (Fig. 21), but its five tubers produced 



■ are vegetative ones and not sexual genera- 



