Carduus and Cnicus 'which appear to be dicecious. 19 



occur, nor have I been able to detect any males amongst these. 

 It is not easy to distinguish between the hermaphrodite and 

 the male ; the only unequivocal test of the latter seems to be, 

 that tlie antherae should have perfect pollen, and that the ovaria 

 should be abortive ; two states of the flowers which it is rather 

 difficult to meet with on the same plant at the same time. 



The stigma does not supply a distinction sufficiently de- 

 cisive ; for although, when the stigma of the female flower is 

 compared with that part in the antheriferous one, a much 

 greater development is perceived in the female, still in the 

 foi-mer it is apparently sufficiently developed for the purposes 

 of impregnation : hence it is not possible, from seeing a few 

 plants with perfect antherae, to say whether the species is dioe- 

 cious or not ; it can only be determined by an examination of 

 numerous specimens. 



There is another source of error : In Cnicus pj-atensis the 

 antheriferous plants which were growing near the females had 

 when gathered the appearance of being males : but having kept 

 them for some daj's and noticed the progress of the develop- 

 ment of the different parts of the flower, it was seen that, when 

 the pollen of a particular flower was entirely dispersed, the 

 stigma became developed nearly as much as in the female 

 flower, although while the style remained covered with pollen 

 it was merely indicated by a line, which induced the idea that 

 the plant was a male : I afterwards found also the antheriferous 

 capitula impregnated, except the florets of the ray, tlie stigmaia 

 of which were not developed nor the ovaria impregnated: 

 whether this is constantly the case, remains for future inquiry. 



Neither in Cnicus palustris nor in acaulis have I ascertained 

 that male plants exist ; in palustris, from the numerous speci- 

 mens examined, I should conclude that they do not, and that 

 this plant therefore consists of hermaphrodites and females, 

 the foi'mer being the most numerous. 



In another plant of the Carduacece, equally common with 

 Cnicus arvensis, I have also found female plants ; this is the 

 Centaurea riigra; but I have not found any that can be called 

 males, as those plants in which the anthers are perfect have 

 perfect seeds. 



The female and hermaphrodite (as it must be called here) 

 differ as the male and I'emale do in Cnicus arve7isis. The fe- 

 male florets are smallest; they project but little beyond the 

 involucrum; their laciniae are but slightly divaricate; their 

 imperfect antherae do not rise above the apices of tiie laciniae 

 of the corolla ; their filaments are never visible : in the her- 

 maphrodite the stamina project so nuich, that at the period of 

 their full vigour the filaments arc seen above the tube of the 



C 2 corolla. 



