198 THE SCOTTISH BOTANICAL REVIEW 



elusion as to the morphological interpretation of this leaf (a) 

 from the anatomical structure. 



It might be advanced in opposition to the view that the 

 leaf (a) is a bract, that later on it does not always stand 

 opposite the peduncle ; this might, however, result from 

 displacement. In the younger stages I saw it in the median 

 position occupying the whole breadth of the inflorescence- 

 primordium (fig. 4). As regards the further development of 

 the male capitula, two facts may be pointed out. Firstly, 

 that the external side (that on which the letter (a) is placed) 

 appeared to be much further advanced than the inner side ; 

 this is seen at once in fig. 4. Secondly, that the arrange- 

 ment of the flowers is not "dichasial" sympodial (as one of 

 the recent authors wrongly states), but corresponds essentially 

 with the other Compositae. One sees quite clearly the broad 

 growing-point of the capitulum (V., fig. 4), from which the 

 individual flowers arise ; some of the outer ones have bracts 

 even now. The characteristic arrangement of the flowers is 

 determined by the fact that the capitulum as a whole is 

 dorsiventral in structure, with a more advanced development 

 on the outer side. 



B. The Female Inflorescences. 



As indicated by Rostowzew, these are dichasially arranged 

 (fig. 5). Each consists of a single flower enclosed by an 

 " envelope " (fig. 8). To understand their constitution it 

 will be necessary to first compare the inflorescences of other 

 Ambrosicz. Here one finds the following series: — 



1. Mixed inflorescences with female marginal florets. 



2. Inflorescences with sexes distinct, in so far that in the 



female only the marginal florets flower, and only the 

 minority of these, while in the male inflorescence the 

 formation of female flowers is entirely suppressed. 



3. There is also a diversity in the arrangement of the 



female and male inflorescences. Whereas the arrange- 

 ment was originally indefinite (botryose), this is re- 

 tained only in the case of the male inflorescences, the 

 female ones showing dichasial arrangement.^ 



^ With regard to diversity of male and female, compare Goebel, " Ueber 

 sexuellen Dimorphismus bei Pflanzen " (" Biolog. Centralblatt," p. 657, 1910). 



