4/8 GENERAL MORPHOLOGY OF PLANTS 



good straw of the English wheat, the high protein content of a 

 foreign wheat, and resistance to the rust.* 



664. Varieties are continually changing. It is a matter of 

 common observation on the part of horticulturists and others that 

 many of the new varieties put upon the market in a few years 

 are so greatly changed, that they no longer resemble the variety 

 as it was originally known and described. In fact several differ- 

 ent new varieties may arise from it in different sections of the 

 country without any effort on the part of the cultivators to de- 

 velop them, and still they may all go by the name of the original 

 new variety. This is due to several causes. First, the variety, 

 although in general breeding true, is variable. Second, when cul- 

 tivated in different localities where climatic, soil and food con- 

 ditions are different, variations are introduced in different direc- 

 tions. Third, the growers, while not attempting to breed new 

 varieties, unconsciously pursue a method which would lead to 

 the production of new varieties. In the selection of seed it is 

 taken from the best plants or from the best fruit. Naturally the 

 ideals of different persons would be different and so their selection 

 would lead in the direction of forming new variations in a few 

 years. 



665. Records. It is very important that one engaged in 

 plant breeding should keep a careful and accurate record of their 

 work so that the pedigree of the races and varieties may be well 

 known. For methods of keeping records reference should be 

 made to some work on plant breeding (see Bailey's Plant Breed- 

 ing, 4th edition, 1906). 



NOTE. The plant breeding by the United States Department of Agricul- 

 ture is concerned with the improvement of the cotton staple, citrous fruits, 

 apples, pineapples, oats, tobacco, etc. 



* See Punnet, R. C., Applied Heredity, Harper's Monthly, December, 

 1908. 



