594 Mr. T. Smith on certain Species of Carduus and Cnicus 



apparently perfect, it did not occur to me that there was any 

 separation of sexes. 



On re-examining this plant, in consequence of Mr. Brown's 

 observations, the striking difference between the male and female 

 flowers, which had formerly induced me to look for some speci- 

 fic difference between the plants bearing them, appeared to point 

 out a very ready mode of examining the nearly allied species by 

 the external appearance of their capitula without the labour of a 

 minute dissection. 



Looking at Cnicus arvensis with this view, I soon found that 

 different patches of it had flowers which presented differences 

 similar to those of the Serratula tinctoria, and dissection con- 

 firmed the external appearances ; by the examination of very 

 many specimens, I ascertained that some plants bore flowers the 

 antherae of which were invariably abortive, and that in others 

 the ovaria as invariably withered without producing seeds. 



A more detailed account of the differences between the male 

 and female flowers is as follows. 



The female florets are somewhat shorter and smaller than the 

 male, particularly the laciniae and dilated part of the tube of the 

 corolla; hence the male capitulum, when in flower, appears 

 much larger than the female. The part of the style which is 

 bearded in the male is shorter in the female, and destitute of pili, 

 except a very few at the base of the fissure ; this fissure in the 

 male opens but little ; in the female it is very much opened, 

 having the margins bent back and the apices recurved ; the 

 apex is divided in the male, but the apices are straight : the 

 male capitulum is more oval, that of the female more cylindri- 

 cal inclining to conical. 



The part of the style which bears the stigma is waved in the 

 female, straight in the male ; in the female flat, bearing the 

 stigma on the edges generally of a deeper purple than the lower 



part; 



