82 STATE HORTICULTURAL SOCIETY. 



parative intimacy with which they react upon each other. If these specu- 

 lations are well founded, it leads us to the conclusion that this impotency 

 among cultivated plants is the beginning of unisexuality, and that such 

 impotency is likely to increase with the greater amelioration of the species. 

 Inasmuch as the female sex-elements are the result of constructive or veg- 

 etative changes, it would seem to follow that such elements would be most 

 likely to be retained in the great vigorousness of cultivated plants, and 

 that the pollen would first show signs of failing. And this is well illus- 

 trated in many cultivated species, for deficiency of pollen is by no means 

 uncommon, while good pistils are almost always present. The only impor- 

 tant exceptions to this statement are the double and sterile flowers, like the 

 roses, carnations, and snowballs; but these plants have been bred directly 

 for their doubleness or sterility, and do not, therefore, influence the present 

 inquiry. The berry-grower knows that all strawberries have pistils or 

 female parts, while an increasing number have no pollen. Potatoes now fail 

 to set bolls because the anthers are deficient in pollen, and horseradish does 

 not set seed, probably for the same reason. One who undertakes to per- 

 form experiments in the crossing of cultivated plants, soon finds that it is 

 more difficult, as a rule, to obtain good pollen than good pistils. 



IMPROVEMENT OF FRUITS INCREASES DEMAND UPON THE TREES. 



An excellent proof that inscreased amelioration of fruits imposes a 

 severe tax upon the energies of the plant, is afforded by the habitual fail- 

 ure of very many or even the greater part of the flowers upon a frait tree 

 in full bloom. Apple flowers are borne in clusters of from five to ten, and 

 yet, except in the crabs, apples are usually borne singly, that is, most of 

 the flowers fail. And trees which bloom full rarely average even one 

 fruit to the cluster. Small wild apples are frequently borne in clusters, 

 and there is every reason to believe that originally all the flowers normally 

 set fruit. With the enormous development in size and other qualities of 

 fruits, the plant is unable to use all its flowers. I am inclined to think, 

 however, that these extra flowers serve a very useful purpose in supplying 

 pollen to those which chance to set, for not only is the supply of pollen in 

 the individual flowers probably becoming less with the improvement 

 of the apple, but it is also probable that more is needed to incite the enor- 

 mous increase in size over that of the inferior aboriginal apple. What is 

 true of the apple is true in various degrees of all orchard fruits, even of 

 the cherry; and it is most graphically shown in the tomato. It is here 

 worthy of remark, also, that probably the chief reason why the bush fruits, 

 as blackberries, raspberries, and currants, do not more rapidly improve in 

 size is because all the flowers upon the clusters still set fruit. All these 

 instances show that cultivation or improvement seriously interferes with 

 the mutual relationship of the sexes, and this disturbance or unbalance is 

 likely to increase rather than diminish. 



A STILL FURTHER ADVANCE — VARIETIES MAY BY SELF-STERILE. 



But it now transpires that not only are some plants impotent or infertile 

 with themselves, but in some cases all the plants of a given variety are 

 infertile among themselves. Thus it has long been known that the Wild 

 Goose plum is usually unproductive when planted in isolated or unmixed 



