582 



BOTANY 



PART I 



In very many cases, e.g. Leguminosae Cruciferae, etc., not only 

 is the nucellus absorbed by the endosperm, but the latter is com- 

 pletely displaced b} r the embryo. The reserve materials are then 

 stored up in the cotyledons or in the whole body of the embryo 

 (Fig. 566). 



Lastly, a structure known as the ARILLUS must be mentioned, 

 which usually stands in relation to the distribution of the seeds. It 

 arises as a succulent and usually brightly coloured outgrowth from 

 the funicle. It grows up around the ovule and ultimately comes to 

 invest the seed more or less completely (Figs. 567 D, 568, 586). 

 An outgrowth in the neighbourhood of the micropyle, which is found 

 in the Euphorbiaceae, is termed a CARUNCULA (Fig. 567 C, #). 



The Fruit ( n ) 



The effect of fertilisation is not only seen in the macrosporangia 

 but extends to the macrosporophylls or carpels. The structures of 



very various form which are 

 formed from the carpels (often 

 together with the persistent 

 calyx and the floral axis) are 

 called FRUITS, and serve 

 primarily to protect the de- 

 veloping seeds. In Gymno- 

 sperms, where the ovules are 

 borne freely exposed on the 

 carpels, no fruits in the strict 

 sense can exist, since no ovary 

 is present. Thus in Cycas, 

 Ginkgo, Taxus, Podocarpus, 



FIG. 569.-Collective fruit of Rosa alba, consisting of Gnetum, and Ephedra W6 Can 

 the fleshy hollowed axis s', the persistent sepals s, Only Speak of Seeds and not of 



< a ifl e D?r^ fruits - When > however, the 



carpels after fertilisation close 



together as in the cones of some Gymnosperms and the berry-like 

 cones of Juniperus, a structure analogous to the angiospermic fruit is 

 formed, and the term fruit may be used. 



A great variety in the development of the fruit in Angiosperms 

 might be anticipated from the range in structure of the gynaeceum 

 described above. The simplest definition of a fruit is the ripened ovary, 

 but difficulties arise in the case of apocarpous gynaecea. 



The product of the individual carpels associated in such apocarpous gynaecea 

 as those of the Rosaceae will here be termed PARTIAL FRUITS or FRUITLETS, while 

 the product of the whole gynaeceum will be spoken of as the FRUIT or the 

 COLLECTIVE FRUIT. The hollowed-out or projecting floral axis bearing the carpels 

 may be included in the fruit. Thus the Strawberry is a collective fruit composed 



