426 



FOURTH GROUP. SEED-PLANTS. 



but occurs also in cymose inflorescences, in which all the flowers are terminal, as in the 

 Labiatae ; its appearance indeed would seem to be determined by the vigorous 

 development of the primary axis of the whole inflorescence, whether the latest 

 ramifications form cymose partial inflorescences or not, as is shown by the Labiatae, 

 and the Scitamineae. 



' A 



FIG. 353. Zygomorphous flower of Polyg ala grandiflora. A entire flower seen from the side after removal of a 

 sepal. B a flower symmetrically divided without the gynaeceum. C the gynaeceum magnified. D transverse section 

 of the ovary. E median longitudinal section of the same. F transverse section of the flower. The letters k k' denote the 

 calyx, c the corolla, st the staminal tube, cp gynophore, f the ovary, g the style, n the stigma, sk ovule, xx the tube 

 formed by the cohering and adhering petals and stamens. 



The fruit in the Angiosperms is the ovary which has developed and become changed 

 physiologically by the effects of fertilisation, and which contains the ripe seeds. In many 

 cases the style and stigma fall off, as in Cucurbita and the Gramineae, and some of the 

 ovules do not develope, so that the number of the seeds is less than that of the ovules. 

 If all the o\ ules of one or more loculi of a plurilocular ovary disappear as the fruit ripens, 

 the fertile loculus only developes, and the others are partially or wholly displaced 

 and become more or less indistinguishable, and the plurilocular ovary produces there- 

 fore an unilocular and often one-seeded fruit ; thus the trilocular ovary of Quercus 

 with two ovules in each loculus becomes an unilocular one-seeded fruit, the acorn ; 

 there is a less complete obliteration of from two to four loculi with the ovules in the 

 ovary of Tilia which has from two to five loculi, the fruit being usually one-seeded. 



Parts on the other hand, which do not belong to the gynaeceum or even to the 

 flower, are changed by fertilisation ; the entire structure thus produced may be called 

 a. pseudocarp, which is therefore composed of a fruit or a number of true fruits, and the 

 peculiarly developed parts surrounding it ; the strawberry for instance is a pseudocarp, 

 in which the axial portion of the flower is swollen into a fleshy pulp, and bears the true 

 small fruits ; in the hip or fruit of the rose the flower-stalk, which is hollowed out into 

 the shape of an urn, surrounds the separate ripe fruits as a red or yellow succulent 

 envelope; in the same way the apple also is a pseudocarp, and the mulberry is 

 composed of an entire spike of flowers, the perianth-leaves of each flower having 

 swollen and become fleshy, and surrounding the small dry fruits ; in the fig the stalk 

 of the entire inflorescence, hollowed out and covered on the inside with fruits, forms 

 the pseudocarp. 



If we accept the definition, that every ripe ovary is a fruit, then several fruits may be 

 produced from one flower, if for instance there are several or many monomerous 



