4o6 ROSACEA 



latter ; but in the pear the ovaries of the carpels are fused with 

 the receptacle, and also united with each other except near their 

 ventral sutures (see the middle of the transverse section, Fig. 

 126, A) and along the styles, which are free. The ovary is 

 inferior and five-chambered : in each carpel are two ovules. 



The upper part (a) of the receptacle is sometimes termed the 

 calyx-tube of the flower ; to it is attached the calyx of five sepals, 

 the corolla of five white petals, and the androecium of many 

 stamens. 



After fertilisation the petals fall off, the stamens and styles 

 wither, and the rest of the flower develops into a peculiar 

 ' false fruit ' termed a povie. 



At the upper part of the pome is seen the ' eye ' of the •' fruit,' 

 consisting of the so-called calyx-tube with the remains of the 

 sepals {n) and stamens (j) attached to it : the withered styles 

 (si) are also frequently visible. The carpels of the gynaecium 

 which constitute the true fruit are fleshy, but their inner walls 

 develop into a thin, tough, horny endocarp surrounding 

 the seeds. The main bulk of the pear for which the ' fruit ' 

 is grown is the very large receptacle which envelops the 

 gynaecium. 



The flowers of the pear are protogynous and have white petals : 

 the pome is top-shaped. Self-fertilisation is possible even with- 

 out the visits of insects : cross-fertilisation is however most 

 common in the chief rosaceous genera. Cross-fertilisation is 

 necessary for the ' setting ' and development of the ' fruit ' of 

 several varieties of pears : after pollination from the same flower 

 or from plants of the same variety no fruits ' set,' hence the 

 importance of planting several distinct varieties in an orchard of 

 pears. 



Most of the cultivated Peaxs appear to be hybrids and selected 

 crosses between several species of Pyrus. 



10. The Apple differs from the pear in possessing flowers with 

 pink and white petals and styles which are united at their bases 



