528 FUNDAMENTALS OF FRUIT PRODUCTION 



the latest phase of its development, it is also very naturally capable of prolifera- 

 tion to root and shoot. The capacity of joint and fruit for persistence and pro- 

 liferation is probably as old as the fleshy character of the family. The persistence 

 of the sterile fruits, at least to maturity, is not a really surprising thing, in view 

 of the preponderatingly vegetative and stem-like character of the bulk of the 

 wall of the ovary. Sterile ovaries occur in many species of angiosperms, but in 

 most of these the carpels constitute the bulk of the fruit. Therefore, when the 

 seeds are wanting in these forms, and the carpels as usual fail to develop, no 

 fruit is formed and the flower bud soon withers and drops off. In Opuntia, on 

 the contrary, even if the seeds and carpellary portion of the fruit do fail to develop, 

 the basal stem-like part may go on, practically unhindered in its vegetative 

 growth, and mature quite normally." 



Between the conditions represented by autonomic parthenocarpy 

 on the one hand and varietal interunfruitfulness on the other there is a 

 series exhibiting practically all possible expressions of the tendency to set 

 and mature fruit. Only a little less extreme than the tendency to fruit- 

 fulness shown by plants vegetatively parthenocarpic is that of plants 

 aitionomically parthenocarpic. Next in the series are the plants that 

 can set and mature fruit if self pollinated and fertilized, though embryo 

 abortion takes place almost at once. These in turn are followed by 

 plants which require varying degrees of development in the seeds that 

 they may properly mature their fruit. Finally there are those that 

 require the maturing of viable seeds along with the developement of their 

 fruits else premature dropping will occur. 



The Value of Seedless and Parthenocarpic Fruits. — Seedlessness in 

 edible fruits is generally regarded as a valuable variety characteristic 

 for commercial purposes. In many cases at least the market is willing to 

 pay a premium for it. Mention of the regard in which seedless grapes and 

 oranges are held is ample evidence. Bananas and pineapples containing 

 seeds would probably find a very limited market. Even a material 

 reduction in the number of seeds would be a great asset in the blueberry, 

 the blackberry, the watermelon, the sugar apple and in many other 

 fruits. On the other hand, in many fruits seedlessness would not be an 

 asset. There would be little advantage in seedless apples or pears, if the 

 carpels remained. It has been pointed out that many fruits of our 

 ordinary plum and cherry varieties are seedless, but this condition is not 

 generally known or even suspected because the bony endocarp (stone) 

 remains unchanged. 



For the grower, parthenocarpy probably is a more valuable variety 

 characteristic than seedlessness. If his fruits are parthenocarpic he is 

 insured against crop failure from self and cross unfruitfulness and, if 

 their parthenocarpy is autonomic, through failures resulting from lack 

 of pollinating agents or pollinating weather, his setting of fruit is more or 

 less guaranteed. It should not be inferred, however, that all the flowers 

 of parthenocarpic varieties set fruit and that aU these fruits mature. 



