114 FERTILIZATION. [SECTION 13. 



to both calyx-tube and ovary, as in Hawthorn (Fig. 273). A flattened 



hypogynous disk, underlying the ovary 

 or ovaries, and from which they fall 

 away at maturity, is sometimes called 

 a Gynobase, as in the Rue family. 

 In some Borragineous flowers, such as 

 Houndstongue, the gynobase runs up 

 in the centre between the carpels into 



a carpophore. The so-called epigynous disk (or Stylopodiumj crowning 



the summit of the ovary in flowers of Umbelliferse, etc., cannot be said to 



belong to the receptacle. 



Section XIII. FERTILIZATION. 



328. The end of the flower is attained when the ovules become seeds. 

 A flower remains for a certain time (longer or shorter according to the 

 species) in anthesis, that is, in the proper state for the fulfilment of this 

 end. During anthesis, the ovules have to be fertilized by tlie pollen ; or at 

 least some pollen has to reach the stigma, or in gymnospermy the ovule 

 itself, and to set up the peculiar growth upon its moist and permeable tis- 

 sue, which has for result the production of an embryo in the ovules. By 

 this the ovules are said to be fertilized. The first step is pollination, or, 

 so to say, the sowing of the proper pollen upon the stigma, where it is to 

 germinate. 



§ 1. ADAPTATIONS FOR POLLINATION OF THE STIGMA. 



329. These various and ever-interesting adaptations and processes are 

 illustrated in the "Botanical Text Book, Structural Botany," chap. VI. 

 sect, iv., also in a brief and simple way in " Botany for Young People, How 

 Plants Behave." So mere outlines only are given here. 



330. Sometimes the application of pollen to the stigma is left to chance, 

 as in dioecious wind-fertilized flowers ; sometimes it is rendered very sure, 

 as in flowers that are fertilized in the bud ; sometimes the pollen is prevented 

 from reaching the stigma of the same flower, although placed very near to 

 it, but then there are always arrangements for its transference to the stigma 

 of some other blossom of the kind. It is among these last that the most, 

 exquisite adaptations are met with. 



331. Accordingly, some flowers are particularly adapted to close or self 

 fertilization ; others to cross fertilization ; some for either, according to 

 circumstances. 



Fig. 364. Flower of a Buckthorn showing a conspicuous perigynous disk. 

 Fig. 365. Vertical section of same flower. 



