22 



THE STRUCTUEE OF FLOWERS. 



position to the petals and sepals. Similarly, in Nigella 

 sativa tlie petals are eight in number, and occupy the same 

 positions as the outermost whorl of stamens of Garidella. 

 They have, then, the eight stamens of the outermost whorl 

 of the androecium superposed to them. 



In Delphinium the stamens and carpels form a continuous 

 spiral, represented by |, or approximately by f. In some 

 cases Braun* found 16 stamens, and the first carpel being 

 the 17th organ, stood superposed to the stamens No. 9 and 



No. 1. In another case 18 

 stamens were developed, so 

 that the first carpel stood 

 superposed to stamen No. 11. 

 Helleborus niger (Fig. 5) 

 has five sepals which emerge 

 and are arranged in quin- 

 cuncial order. There are 

 twenty-one nectariform pe- 

 tals, i.e. one cycle of the 

 ■^-j- arrangement, grouped as 

 in the accompanying dia- 

 gram. The petals 1 to 8 

 and 9 to 16 would correspond approximately to two cycles 

 of the f type. Radial rows of stamens then follow on the 

 same lines as the petals. 



Eranthis hyemalis has, as usually regarded, a 5-8-merous 

 coloured calyx. A pair of staminodes stand superposed to 

 each member of the outer whorl. Stamens follow along the 

 radial lines, of which six terminate in carpels. 



Aguilegia vulgaris, or the Columbine, has the sepals, as 



* Al. Brann on Delphinium (Pringsheim's Jahrl. f. Wiss, Bot., 1857, 

 i. 206), referred to by Henfrey, Morphol. of BalsaminecB, Journ. of Lin. 

 Soc, iii. 159. 



Fig. 5.- Diagram of Helleborus niger. 



