30 



TROPICAL AGRICULTURE 



Fertilisation Stigma ill such a Way as lo fertilize the flower^ that is, to 

 flowers. cause the pistils to develop into fruit with seeds in them. 

 Without this fertilising process taking place, no fruit can 

 be formed, and the flowers would wdther, die, and drop off 

 the tree. As soon as the ovules become fertilized by the 

 pollen, the compound pistil of the orange begins to grow 

 into fruit. The sepals remain permanently attached to 

 the stalk at the base of the fruit ; the petals wither and 

 drop off, as do also the stamens ; the ovary grows rapidly 

 to form the fruit or seed envelopes, and the ovules be- 

 come in time the seeds from which new plants may be 

 raised. 



Numbers of flowers possess an arrangement of their parts 

 similar to that of the orange ; and from the description al- 

 ready given, it will not be difficult to determine which are 

 the floral envelopes, as the sepals and the petals are col- 

 lectively called, and which are the stamens and pistils. But 

 very many flowers differ greatly from the type of which the 

 orange may be taken as an example. Thus, for instance, 

 instead of the floral envelopes being composed of two series 

 of organs, there may be only one, as in the case of the lilies, 

 and this single envelope is called the perianth, and it is 

 made up of perianth leaves, which are usually highly 

 coloured. The parts of the calyx, corolla and perianth may 

 be separate leaf-like organs, or they may be joined together, 

 making envelopes of an infinite variety of forms. The floral 

 envelopes, too, may be inconspicuous or entirely wanting. 

 In the case of the cocoe or tania, the iitfiorescence — which 

 is the name given to the collection of flowers on the flower- 

 ing stem — consists of a central axis on which are set num- 

 bers of stamens above and pistils below ; each stamen is 

 a stajuinate flower and each pistil is -x pistillate flower ; there 

 is no calyx or corolla or perianth, but the inflorescence 

 is protected by a large, yellowish, leaf-like envelope called 

 a spathe. 



In some plants the stamens and pistils are in different 



The floral 

 envelopes 

 may be 

 wanting. 



