528 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



the nature of the cell content. The circle of vascular tissue 

 surrounds this dome of pith and, branching near the summit, 

 sends new strands into the different structures as they are formed. 

 This is shown in the section in the strands on each side of the pith. 

 The end of the axis is early identified as a small blunt elevation 

 and below it are found other excrescences in the axils of small 

 bracts. These slight elevations are the primordia of the flowers. 

 The description of the development of a single flower of the inflor- 

 escence follow^s. 



The parts of a flower develop from the end of the stem or the 

 receptacle and a typical receptacle is a rounded or flat surface on 

 which the floral members develop. The small elevation destined 

 to become a flower in the apple, is found to consist at first of a 

 dome of tissue which however soon becomes cup-shaped and 

 presents a hollowed appearance. The tissue lining this cup is 

 meristematic. The cells beneath this meristematic layer are a 

 continuation of the axis or stem on w^hich the flower is produced. 

 Within this structure avascular system is differentiated, demarking 

 the cortex and pith. Growth occurs on the periphery of this cup 

 and particularly at five points, marking the primordia of the 

 sepals. The origin of the sepals is of Interest In relation to the 

 development of the fruit. 



Le Maout and Decaisne (19) state that in many plants the 

 receptacle dilates into a cup which represents a calyclnal tube, 

 better called receptacular cup, over which the torus is spread and 

 that hypertrophy of the receptacle Is particularly striking in or- 

 chard fruits. The torus is considered the periphery of the receptacle 

 but the term for most authors is synonymous with the receptacle 

 and is so considered here. The sepals then begin their growth as 

 five outgrowths of the torus. According to this view the apple 

 flower does not possess a calyx tube, the calyx being limited to 

 the five sepals. The calyx therefore does not form any part of 

 the flesh of the apple and changes but slightly if at all as the fruit 

 develops. 



The torus grows rapidly by intercalary growth beneath the 

 sepals and as growth proceeds the rccei)tacular cup becomes more 

 highly de\el()ped, producing next the petals, then the stamens, and 

 finally the pistils. In plate 35 different stages in the develop- 

 ment of the (lower are shown. Figure 3 is of a very young flower 



