BREEDING OF VEGETABLES 241 



means of determining the genetic nature of any particular 

 variety or strain. 



Factors A, C, E, (Gc) and L\ appear absolutely coupled and 

 may, therefore, be considered to be a single factor with several 

 separate expressions. This factor gives salmon-pink or rose color 

 to the flower, and to the leaf axil, and to the stem in the presence 

 of D; purple dotting on seed-coats in the presence of F and B, 

 with reddish dots when B is absent and F is present; yellowish 

 green to grayish brown seed-coat color, brown hilum; indent 

 peas in the presence of L 2 . 



The results of examining many thousand F 2 generation progeny 

 indicate that factors A, B, (Fa), /, (Le), G, and R are indepen- 

 dently inherited. 



Four groups of linked factors were found. These, according 

 to the factorial notation used by White, are: 



GROUP PARTIALLY LINKED RATIO OF NON-CROSSOVERS 



TO CROSSOVERS 



1 (Bl)S 8:1 



2 A(Lf) 7:1 



3 R(Tl) 63:1 



4 GO Undecided 



BEANS 



Some Classification Characters. The species 1 of garden beans 

 most commonly grown are Phaseolus vulgaris and P. lunatus. 

 The former is divided, from the standpoint of use as food, into 

 snap and shell beans, although there is some overlapping in these 

 groups. Shell beans are sometimes used as snap beans and vice 

 versa. Time required to mature, habit of growth, whether climb- 

 ing or bush, and size of plant are characters always described by 

 commercial seedsmen. Length of bearing period is also an im- 

 portant character. Commercial growers sometimes desire varie- 

 ties which may be harvested in a few pickings but for the home 

 and general gardener, a variety with a longer bearing period is 

 usually preferred. Size and shape of pod, number of seeds per 

 pod in the case of snap beans, quality and color of the pod, 

 are used in classification; with snap beans, stringless, fleshy, 

 fine-grained pods are most desirable. The ease with which dry 



1 For a discussion of the classification of garden beans and a description 

 of varieties see TRACY, W. W., American Varieties of Garden Beans, U. S. 

 D. A., B. P. I. Bull. 109, 173 pages, 1907; JARVIS, C. D., American Varieties 

 of Beans, Cornell Agr. Exp. Sta. Bull 260: 149-255: 1908. 



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