MOEPHOLOGY OF EEPEODUCTIVE "OEGANS 139 



petaloid or coloured as in Galtlia and Anemone. Its caly- 

 cine nature in these cases can be determined by a comparative 

 examination of other closely related flowers, as the Hellebore, 

 where the true petals have undergone a curious change of form. 

 In some cases the calyx appears absent, as in the Valerians and 

 most UmbelliferEe. It is, however, only partly lost, being united 

 throughout most of its length with the ovary, and only exposing 

 a rim at the top of the latter. 



Suppression of a whorl of sporophyUs is not uncommon ; 

 in such a case the flower is said to be iinperfect. The andrceoium 

 or gyncecium may be thus suppressed, in either of which cases 

 the flower is unisexual ; if both are suppressed, as in certain 

 florets in some of the Compositse, the flower is termed neuter. 

 When the stamens are abortive it is xnstillate {fig. 258) ; when 

 the pistil is absent it is staminate (fig. 257). 



Fig. 257. 



Fig. 258. 



Fig. 257. Catkin of staminate iiowers of a species 

 of Willow (Salix). Fiij. 268. Catkin of pistil- 

 late or carpellary flowers of the same. 



b. Suppression of one or more Members of a Whorl. — This 

 is a very common cause of deviation from typical structure ; 

 we can here bring forward only a few examples. 



This suppression of parts is most frequent in the gyncecium. 

 Thus in Ehamnus {fig. 251) we have five sepals, five petals, five 

 stamens, and three carpels ; here two carpels are suppressed. In 

 the Heartsease {fig. 259) we have again a pentamerous flower, so 

 far as the calyx, ooroUa, and androecium are concerned, but only 

 three carpels, two carpels being here suppressed ; in Leguminous 



