ANGIOSPERMS. 



535 



in a flower, making the plant uniaxial. When this is the case a sympodial or 

 cymose inflorescence is usually developed, new axes with terminal flowers arising 

 beneath the first flower; but it is more common for only axes of the second, 

 third, or a higher order to terminate in a flower, so that the plant may in this 

 respect be termed bi-, tri-, or multi-axial. 



While in Gymnosperms the flowers are typically unisexual or diclinous, herma- 

 phroditism largely prevails among Angiosperms, although monoecious and dioecious 

 species, genera, and families are not uncommon. The male flowers are sometimes 

 essentially difl"erent in structure from the female flowers (as in Cupuliferse and 

 Cannabinese), but in most cases the unisexuality arises merely from the partial or 

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

 respects constructed on the same type (Fig. 357, 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 are 

 completely developed in hermaphrodite flowers and functionally perfect, fertilisation 



Fig. 358 .—Asaritfit arttadense; A the flower cut through lengthwise, / the perianth ; B horizontal section of the flower 

 above the ovary ; C horizontal section of the sex-locular ovary ; D a stamen with its lateral anther-lobes a. 



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

 ovules of another flower (as in Orchideae, Cotydalis, &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 

 manner that the ape^ of the axis is placed at the bottom of the hollow (p. 220), while 



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