370 UOTANY or CROP PLANTS 



conditions, the fruit and leaf buds are differentiated in early 

 July, and in early varieties, even by the latter part of May. 



The form of the tree, nature of twigs, branches, bark and 

 leaves vary a great deal in the many varieties of apples. 



Leaves. — These are simple, alternate, and toothed or 

 lobed; the stipules are free from the petiole. 



Inflorescence. — It will be recalled that the buds contain- 

 ing flowers are mixed buds. Hence, when each opens there 

 is developed a very short axis bearing closely crowded leaves 

 and flowers. On this axis, the flowers are apical, the leaves 

 basal. The flowers may be so crowded that the cyme is 

 umbel-like in appearance. In most cases, the inflorescence 

 is terminal, but, as has been indicated above, it is axillary 

 in some varieties. The number of flowers in a single mixed 

 bud may vary from two or three to eight or ten. As a rule, 

 but one flower matures its fruit, thus illustrating the struggle 

 for existence among the different individual flowers. 



The determinate inflorescence, cyme, of appl^ is not always 

 definitely so. It will be remembered that in the cyme t)^e 

 of inflorescence the flowers open in order from the inside 

 outward. Sometimes the central flower is tardy in its 

 development, and often the central and some of the laterals 

 may open simultaneously. 



Flowers and Their Development. — The development of 

 the apple flower (Yellow New,ton) has been worked out by 

 Kraus. A longitudinal section (Fig. 155) of a growing axis 

 shows a number of bracts and bud scales surrounding it; on 

 the sides of the axis, appear the primordia of flower buds and 

 leaves. The primordia of sepals are the first to appear. 

 The torus develops especially toward the outer edge by a 

 growth of the cells beneath the developing calyx, and finally 

 takes on a concave shape. The torus continues ±0 uprise 

 during the development of petals and stamens, both of which 



