75 



XVIII. — On some Relationships of Inflorescences. By G. Sigerson, 

 M. D., Ch. M., F. L. S. [Abstract.] 



[Read June 10, 1867.] 

 I. 



The relationship which exists between the inflorescences of plants is a 

 subject of not a little importance, for several reasons, and yet it is one 

 which has not hitherto received much attention from scientific botanists. 

 As helping to throw light upon obscure affinities of orders, and as 

 symptomatic of the position and subordination of plants and divisions, it 

 appears to merit more consideration than it yet has received, and on 

 this account I have ventured to put together some suggestions on the 

 subject. These remarks, however, must be regarded as merely an out- 

 line or an abstract, more or less imperfect, of that mode of dealing with 

 the question which has appeared to give the surest clue to some of its 

 intricacies. 



Heretofore, observers appear to have taken the capitulum as their start- 

 ing point in dealing with some relationships which are not obscurely ap- 

 parent, as well as with a few other ^^'-relationships, the correctness of 

 which does not seem clear and evident. In the capitulum the florets are 

 sessile. If we suppose them elevated upon footstalks, it has been said, 

 an umbel will be the result. Again, if the receptacle of the capitulum 

 be supposed sufficiently elongated, we shall have the spike produced as 

 a consequence ; and from the spike, by the development of the flower 

 stalks, the raceme may be supposed to be formed. If, however, the 

 inferior peduncles be prolonged to a greater extent than the upper 

 ones, then we shall have the corymb ; whilst, supposing the peduncles 

 to branch, the panicle becomes evident as a result of the ramification of 

 this form. 



To this it has been added, that the cone is a modification of the 

 spike, the rachis in this instance bearing persistent scales; and the 

 spadix is said to result from the rachis of the spike becoming fleshy, 

 and bearing the flowers more or less imbedded in it. 



Whilst many of the above relationships appear to be natural enough, 

 there are some, especially the latter suppositions, which cannot well be 

 regarded as unexceptionable. There is no particular order of subordi- 

 nation marked out ; whilst, in assuming the capitulum as a sort of start- 

 ing point or centre, whence the several inflorescences are supposed to 

 have radiated, we must ignore those forms which preceded it, and 

 consequently neglect many relationships by which they are allied with 

 higher forms. 



After a careful analysis of the lower forms of inflorescence 

 amongst Phanerogamia, from which many of the more complex forms 

 may be deduced, it appeared to me necessary to revert to cryptogamic 



