OF INFLORESCENCE. Go 



depend either upon the mode of inflorescence, or upon 

 what we confound under the name of peduncle — the 

 several different degrees of the ramifications. In gene- 

 ral they present a more cylindrical form in racemes and 

 spikes, and have a tendency to dilate at the top in 

 umbels. 



In the former, the principal difference which they 

 present is that of being either really cylindrical, or more 

 or less compressed ; this compression in some cases, 

 goes so far as to give them a form, expanded into a 

 strap* as in certain species of Eugenia and Eucalyptus. 



Sometimes this strap-like form appears peculiar to 

 the species, without our being able to determine the 

 cause : — sometimes it seems to result from the compres- 

 sion of neighbouring organs ; thus the peduncles which 

 proceed from several bulbs are compressed, at least at 

 their base, by the pressure of the coats : sometimes it 

 appears to be owing to the peduncle being bordered by 

 a foliaceous membrane ; this seems to take place in 

 RascuSf and more evidently in Urtica membranacea ; 

 in this case the flowers arise from the middle of the 

 membrane which represents the true pedicule. Some- 

 times the compression is owing to a kind of dilatation 

 or foliaceous expansion of the peduncle, as in Xylophylla 

 (PI. 16, fig. 1). When the peduncles are much com- 

 pressed, the pedicels usually arise from the angles, and 

 not from the plane surfaces — for example, in Xylophylla; 

 whence it results that they strictly alternate, and if 

 they are near together their flowers are said to be 

 distichous. 



In umbels, or umbelliferous cymes, the peduncles have 

 a tendency to be dilated at the summit; and this is con- 

 nected with two circumstances : it is large in proportion 

 as the number of flowers which ought to be found placed 

 upon the peduncle is large ; it is also generally larger 



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