CHAPTER XXII 



THE FRUIT 



JUST as the development of the flower culminates with 

 the ripening of the spores and the production of the 

 gametes followed by fertilization, so the development 

 of the fruit culminates with the ripening of the seeds, 

 which are the ovules after the zygote (fertilised egg) 

 has developed into the embryo of the new plant. 



Development of Seed from Ovule. After fertilisation 

 the zygote divides and forms a (usually spherical) 

 embryonal cell towards the centre of the embryo sac, 

 and a stalk (suspensor) connecting this with a basal 

 cell, which remains attached to the micropylar end of 

 the sac (Fig. 62, A). The cells of the suspensor divide 

 at right angles to its length and elongate, pushing the 

 embryonal cell down into the endosperm I tissue which 

 is formed by the rapid division of the secondary nucleus, 

 food substances being poured into the sac through the 

 vascular bundle. Between the numerous nuclei which 

 arise from this, cell walls appear, thus filling the sac 

 with parenchymatous tissue. 



The embryonal cell now divides, and the mass of 

 cells to which it gives rise forms the embryo proper, the 

 suspensor ceasing to grow (Fig. 62, B). In a dicotyle- 

 dinous plant (the majority of the flowering plants) 

 two rounded projections arise on the free end of the 

 embryo (Fig. 62, C), and these develop into the two 



1 From Greek evdov and OTrepua, " inside the seed." 

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