THE FLOWER 



105 



Fig". 98.— Floral Diagrrams 

 , Bambusa. b, Ordinary type of grass. 



are valvate or imbricate. Such floral diagrams are 



said to be empirical, as they represent the actual 



condition of flowers. When a diagram shows not 



only the parts of a flower actually present, but also 



suppressed parts, it is 



said to be theoretical. 



The suppressed parts 



are reprtsented in the 



diagram by dots to show 



the normal position of 



the absent parts (fig. 



98). 



Floral Formul/E. — 

 The number, cohesion, 



and adhesion of the segments of a flower may also 

 be represented by a formula (fig. 99). Thus the 

 formula K2 + 2, C4, A2 + 4, G@ represents the struc- 

 ture of the flower of Mustard; K2 + 2 indicates that 

 the calyx consists of four sepals, arranged in two 

 whorls of two each, and that it is poly- • 



sepalous and inferior; Q indicates that 



the corolla consists of four petals in 



one whorl, and that it is polypetalous 



and hypogynous; A2 + 4 indicates that 



the androecium consists of six stamens, 



arranged in two whorls, two in the 



outer and four in the inner whorl, and 



that they are free and hypogynous; 



and G^' indicates that the gynoecium consists of two 



carpels in one whorl, and is syncarpous and superior. 



Compare the formula with the floral diagram (fig. 99). 



The formula K(5), |C(5), Asj, G® represents the 



structure of the flower of Datura, namely, the flower 



has one whorl of calyx with five sepals, gamo- 



sepalous, inferior; one whorl of corolla with five 



Figf. gg. — Floral Dia- 

 gfram of Cruciferae 



