82 The Potato 



pure. Perhaps it would be safest to look upon the results 

 as showing certain tendencies in heredity, rather than as 

 accurate character analysis. Salaman ^ ^ of England and 

 East ^ of this country have done most of the mendelian 

 work on the potato. A resume of their work will be given 

 in the sections that follow : 



Stem color. — Some varieties of potatoes have pure green stems, 

 while others have traces of purple varying from light purple to al- 

 most black. The purple seems to be partially dominant over the 

 green. The pure greens appear to be recessive and to breed true. 

 Salaman ^ found that the deep purple stem color of the Congo gave a 

 good mendelian segregation. No ratios were given. 



East {loc. cit.) reports the following: One purple-stemmed vari- 

 ety when selfed gave only purples. Four piu-ple-stemmed varieties 

 gave both purple and green when selfed. Four green varieties when 

 selfed gave only green. A pure green X a heterozygous purple gave 

 6 purples and 7 greens — RR X DR. 



Flower color. — Potato flowers may be either white, heliotrope or 

 shades of purple. The color is usually confined to one or the other of 

 the surfaces of the flower. In all the domestic varieties studied by 

 Salaman {loc. cit.) the color was limited to the upper surface. S. tube- 

 rosum had color only on the lower surface. In S. rcrrucosum the 

 color appeared to be present on both sides of the flower. 



East {loc. cit.) reports one purple which broke up into 14 purples 

 to 5 whites when selfed. He says that purple is probably dominant 

 to white. 



Color in the tubers. — The skin of the tuber may be either white 

 (yellow), red or purple. The flesh in like manner may be either 

 white or colored. Purple-skinned varieties often have white flesh, 

 and white-skinned sorts may show traces of color when cut open. 

 Salaman ^ says that these colors are all due to pigments dissolved in 

 the cell sap. 



' Salaman, R. N. The Inheritance of Color and Other Characters in 

 the Potato. Journ. Gen., Vol. 1, 1910-11. 



= Salaman, R. N. A Lecture on the Hereditary Characters of the 

 Potato. Roy. Soc. Hort. Journ., 38 : 34-39 (1912-13). 



3 East, E. M. Inheritance in Potatoes. Amer. Nat., U: 424-430 

 (1910). 



