ANGIOSPERMS. 



467 



entire abortion either of the androecium or the gynajceum, the flower being in other 

 respects constructed on the same type (Fig. 327, A); and in such cases it also 

 frequently happens that hermaphrodite flowers are developed in addition to the 

 male and female (polygamous species, as the ash, Acer, Saponaria ocymoides, &c.). 

 But even in the greater number of cases where the male and female organs e 

 completely developed in hermaphrodite flowers and functionally perfect, fertilisation 

 takes place by the conveyance of the pollen of one flower to the gynseceum of 

 other flowers or even of other individuals of the same species, because either polli- 

 nation within tHe same flower is impossible in consequence of special contrivances 

 (such as dichogamy), or because the pollen is potent only in the fertilisation of 



Fig. ■^^■;.—Akebia qttiiiata; A part of an inflorescence, i female, 6 male flowers; /> a male flower cut through leng^th- 

 wise, fits sterile carpels; C horizontal section^ of a female flower (magnified); D horizontal section of a male flower; 

 K gynaceum of the female flower with the sterile stamens a; Fan ovary cut through horizontally ; G an ovule ; // horizontal 

 section of an anther; a (in /> and C) the outer, a' the inner stamens, c (in £) the carpels ; p {in B and C) the perianth. 



ovules of another flower (as in Orchideae, Corydalis, &c.). To these phenomena 

 we shall recur more in detail in the Third Book, when speaking of the physiology 

 of sexual reproduction. 



While in Gymnosperms the floral axis is usually elongated to such an extent 

 that the sexual organs, especially if numerous, are evidently arranged one above 

 another in alternate whorls or in spirals, — in Angiosperms, on the contrary, the 

 floral axis which bears the floral envelopes and sexual organs is so abbreviated 

 that space can only be found for the various foliar structures by a corresponding 

 expansion or increase in size of the receptacle or torus ; this receptacle swells even 

 before and during the formation of the floral leaves in a club-shaped manner, and is 

 not unfrequently expanded flat like a plate or even hollowed out like a cup in such a 



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