254 



BOTANY OF THE LIVING PLANT 



coherent gynoecium over that with separate carpels lies in the more 

 effective protection and nutrition of the ovules. But it presents 

 fresh difficulties in the liberation of the seeds when ripe. 



The structure of the gynoecium is further complicated by the fact 

 that the carpels are frequently sunk into the tissues of the enlarged 

 receptacle, a condition which serves still more completely the purpose 

 of protection and nutrition of the ovules ; for it brings them closer 

 to the nutritive supply that comes from below, and makes a thicker 

 protective wall possible (Fig. 187). Naturally this goes along with 

 fusion of the carpels. The result is a massive body formed partly 



FIG. 202. 



To the left, median section of the flower of Saxifrage, showing the carpels half 

 sunk in the receptacle, and coherent for the greater part of their length. (After 

 Figuier.) A, similar section of the Quince, showing apparently inferior ovary, but 

 the styles and stigmas separate. B, same for Apple, showing styles united, but 

 stigmas still separate. (After Warming.) 



from the floral receptacle, partly from the carpels. It is syncarpous, 

 and being apparently below the other floral parts it is styled inferior. 

 The development of such a gynoecium has been traced in the structu- 

 rally simple, though highly specialised case of Chrysanthemum, where 

 there is only one cavity of the ovary, and one ovule (Fig. 188, p. 239). 

 But in relatively primitive cases there are several loculi, corresponding 

 to the number of the carpels, and there may be many ovules in each, 

 as in the Quince (Fig. 202, A) or Iris (Fig. 203). 



Various intermediate states serve to explain how the inferior syncarpous 

 ovary may have come into existence. For instance, in Saxifraga the two 

 carpels are united through about half their length, and are partially sunk 

 below the other parts in the tissue of the axis (Fig. 202). Other intermediate 

 states are seen in the Pomeae. For instance, in Cotoneaster the flower is little 

 removed from the perigynous state. In Cydonia the ovary is more dis- 

 tinctly inferior, but the carpels are not fully united, each having a separate 

 style, while the apex of the abbreviated axis lies in a deep depression between 

 them (Fig. 202, A). In the closely related Apple their fusion is more advanced, 

 so that there is a common style, but a distinct stigma for each carpel (Fig. 202, 

 B). The last step of fusion would be their coalescence to a single stigma, as is 



