HERBACEOUS AND WOODY DICOTYLEDONS 409 



Flowers and fruit. The flowers in most common apples are 

 borne in clusters, on dwarf or spur shoots, which occur as lateral 

 shoots on the more rapidly growing leafy branches of the tree. 

 The buds which bear the flowers are mixed buds, bearing ter- 

 minal flower clusters and a few leaves at the base of the year's 

 growth. Since the spur shoot 

 is usually terminated by a 

 flower cluster, its growth in 

 length from this bud is stopped, 

 but may be continued by a lat- 

 eral bud, which may in turn 

 produce a terminal mixed bud 

 and bear flowers and fruit. The 

 flowers, unlike those of the 

 rose and cherry, are epigynous 

 (Figs. 258, d and e, and 259, e), 

 so that the receptacle and ovary 

 are closely adherent in the for- 

 mation of the fruit. 



Cross-pollination takes place 

 normally by insects, but some 

 varieties are self -sterile ; that 

 is, they fail to be fertilized 

 when pollinated with their own 

 pollen. In such instances the 

 self-sterile variety, in order to 

 set its fruit, must be crossed 

 with pollen from some other 

 variety with which it is fertile. 

 In the development of the fruit the ovary wall forms the mem- 

 branous core and a portion of the flesh immediately surrounding 

 it. The outer and greater portion of the fleshy part of the apple 

 is, however, developed from the receptacle. 



In the apple and many other members of the rose family the 

 seeds are disseminated mainly by animals, especially birds, which 

 eat the fruits and the seeds. The hard seeds resist the action 

 of the digestive juices and are cast out with animal excrements, 



FIG. 259. Flower and fruit of the 

 cherry and the apple 



b, perigynous flower of the cherry, in 

 section; c, section of the drupe; e, epig- 

 ynous flower of the apple, in section; 

 f, section of the pome 



