48 



Cohesion. 



Flowers. 



Although the apex of the floral axis as a rule ceases to grow 

 at a very early stage in the development of the flower, excep- 

 tional cases are known in which this axis has continued to 

 grow, and we find a green leafy shoot growing apparently out 

 of the centre of the flower. Very rare cases are also known 

 in which buds have been developed in the axils of the floral 

 members, just as they are usually developed in the axils of 

 normal leaves. 



44. Owing to the very limited 



growth of the floral axis and to the non-development of its 

 internodes the floral parts are, as has already been noted, 

 crowded close together and in many cases this crowding 

 results in the young members, which originate separately on 

 the receptacle, coalescing at their bases, and they then grow 

 up together instead of separately. This is how a gamosepalous 

 calyx, or a gamopetalous corolla, for instance, arises. When 

 members belonging to the same whorl become thus fused 

 together the phenomenon is termed cohesion and the members 

 are said to be connate. 



Members belonging to adjacent whorls also often become 

 fused together and we find, for example, stamens fused with 

 petals, the stamens looking as if they had grown out of the 

 corolla. In such a case we say there is adhesion. Members 

 which are thus adnate appear to originate not directly from 

 the receptacle in the usual way but at some distance from it, 

 their apparent point of insertion having been carried, as it 

 were, away from the receptacle. Cohesion then is the union 

 of members belonging to the same whorl, adhesion the union 

 of those developed at different levels, while members which 

 are neither connate nor adnate are said to be free. 

 , 45. When there is no adhesion 



an( l the se P a l s > petals and stamens all arise directly from the 

 receptacle, these members obviously originate directly below 

 the gyno3cium. The sepals, petals and stamens are then 

 said to be hypogynous, or inferior, and the gyncecium is free and 

 superior. The entire flower may also be described as hypogynous. 

 When, however, there is some degree of adhesion and the 

 petals and stamens, instead of springing from the receptacle, 

 appear to spring from the calyx-tube, the apparent insertions 

 of the sepals, petals and stamens are no longer directly 

 below the gynoecium, but are carried out away from the 

 receptacle and form a circle around the gynoecium. In 

 this case the sepals, petals and stamens are per igy nous 

 and the flower itself is said to be perigynous. Here, however, 



