I08 MINNESOTA STATE HORTICUF.TURAL SOCIETY. 



CROSSING FRUIT FLOWERS. 



MAX PFAENDER, ST, ANTHONY PARK, 



The crossing of flowers opens a new field to the horticulturist. 

 It vastly increases the opportunities in plant improvement. The 

 raising of seedlings followed by careful selection is the usual way 

 of improving our fruits and other plants. Here we depend entirely 

 upon the very slight and comparatively insignificant variations 

 which are found in all plants. Also, in this process we get the 

 characters of one common parent if the plant is self-fertilized, or 

 from two parents of the same variety if the plant is insect-pollinated, 

 or dioecious. The chances of a good seedling from naturally 

 pollinated parents are very meager, and we never know just what 

 we will get. But if we resort to crossing we can just about tell 

 what the offspring will be. We can combine in the offspring the 

 desirable characters of the two parents. We can combine hardiness 

 with prolificness, quality or disease-resistance. ]\Iore often we 

 resort to crossing in order to break the type : i. e., to make the 

 species produce a great number of great and deviating variations. 

 From these many variable forms we can select the best and start 

 to fix the type, which is done by in-breeding and selection — or we 

 propagate the new and desirable variant by cuttings or graftage. 

 Since we can do this, would it not be much more profitable to cross 

 fruit flowers with a definite end in view than to leave our affairs 

 in the hands of chance and keep on raising seedlings? I do not 

 want to discourage the raising of seedlings, b;it I would like to 

 impress upon you the fact that judicious crossing followed by care- 

 ful selection offers greater opportunities and a much more fas- 

 cinating field. 



The theory of plant breeding is still in its infancy, and very 

 little is understood concerning the laws which govern thi^ art: so 

 I shall just concern myself with the practical side of crossing. 



First, we must understand the. structure of the flower with which 

 we are working. Most of the fruit flowers, as strawberrv, rasp- 

 berry, plum and apple flowers, are quite simple to understand. 

 In the center of the flower we have one or more pistils, which on 

 their top end bear the stigma, or receptive area. In pollination 

 the pollen falls on this receptive area, then the pollen grai i breaks 

 open and sends a long slender tube down through the pi>til. At 

 the bottom of the pistil are located the ovules, and these are then 

 fertilized by the contents of the pollen tube passing into and fusing 

 with the contents of the ovule. This, then, is fertilization. (See 



Figure i.) 



Surrounding the ])istils we have one or more circles of stamens. 



