ALTERNATION OF POSITION 



41 



the dots are omitted it is called Empirical. Frequently, also, a dot is 

 placed above the diagram to indicate the position of the plant-stem on 

 which the flower is borne, this being the Superior or Posterior side of 

 the flower, while underneath it is often indicated the leaf or bract in the 

 axil of which it is situated, this being the Inferior or Anterior side of the 

 flower. 



Fig. 43. Diagram of transverse section of Geranium, showing the alternation of parts. 44. Vertical 

 view of Illi-pe, one set of stamens alternating with, the other opposite to, the corolla-lobes, and several 

 of the stamens aborted. 45. Flower of Clayionia with outer set of stamens suppressed. 46. One of 

 the remaining stamens anteposed to petal. 47. Typical flower of Sedum. 48. Slightly irregular 

 corolla of Pelargonium. 



Indication of the Numerical Plan by Fonnula. — The manner of 

 indicating by formulae the number of parts in calyx, corolla, androecium, 

 or gynaecium has already been indicated. It will now be seen that by 

 a combination of these expressions, the entire plan of the flower can 

 be indicated by a single formula. K3, C3, A3 + 3, G^ indicates 3 sepals, 

 3 petals, 2 circles of 3 stamens each, and 2 carpels. K3, C3, A^ + 0, G^, 

 would indicate that the second circle of stamens had suffered suppres- 

 sion, but each of the first circle had divided into three. In a diagram, 

 the positions of the suppressed stamens would be indicated „ „ 

 by dots, while the doubled set remaining would be indicated in J . . u 





pairs, thus: The letter n, in place of a figure, as in the follow- 

 ing formula, K5, C5 A5 -|- n, G^, indicates that the number of parts of 

 that kind (in this case the stamens of the second circle) is not constant. 

 Law 2 : Alternation of Position. — The parts of each circle alternate in 

 position with those of the adjacent circles. In other words, each part of 



