274 BREEDING CROP PLANTS 



bud sports have been found, and in some cases these have been 

 used as the foundation of improved races. To justify a method 

 of breeding founded upon their utilization, such bud sports 

 must occur frequently enough to pay for the trouble of making 

 a systematic search for them. 



A review of the experimental evidence is of considerable 

 interest, for this is the only means we have of deciding whether 

 the selection of particular trees or branches for propagating pur- 

 poses is a reliable means of producing new varieties. Of the four 

 apple bud sports mentioned in Table LXVIII the chief changes 

 were in the color of the fruits. In the Isabella grape several 

 sports were obtained which produced black grapes of larger size 

 than Isabella, and which excelled in sweetness (Powell, 1898 cited 

 from Dorsey, 1916). Dorsey (1916) records two large-fruited 

 variations in the Concord grape which arose as bud sports. 



Instances of bud variations in ornamental horticultural plants 

 are quite common. As an example of their frequency, the work 

 of Stout (1915) will be briefly discussed. Extensive asexual or 

 clonal selections were made in Coleus and numerous color changes 

 were isolated as well as changes in leaf shape. The same varia- 

 tions were obtained through bud sports as by seed reproduction. 

 Some clonal lines sported much less frequently than others. 



The work on citrus fruits (Shamel and others, 1918) which has 

 been carried on in California, has drawn the attention of many 

 horticulturists and plant breeders to the subject of bud sports and 

 their place in correct fruit-breeding methods. Valencia oranges 

 were originally introduced from three sources, but all have proved 

 of similar type and are now called Valencia. From this variety 

 12 important strains originating as bud sports have been isolated. 

 As a rule, single off-type branches produce fruits showing charac- 

 ters which are different from the fruits borne on the remainder 

 of the tree. Many of these sports are of highly undesirable type. 

 The Washington navel orange was introduced from Brazil in 

 1870 by the Department of Agriculture at Washington. Thir- 

 teen distinct strains have been isolated through bud selection. 

 Thompson, one of these strains, has proved a very desirable type. 

 Likewise, bud sports have occurred in the grapefruit which 

 was introduced in California from Florida in 1890. The Marsh 

 is the best of six strains which were obtained by selecting bud 

 sports. Similarly bud sports have occurred in lemon orchards. 

 Shamel (1919) records an occurrence of a sporting branch in a 



