XIV] 



EMPIRICAL AND THEORETICAL DIAGRAM 



127 



and this evidence is strengthened by further comparisons 

 of allied forms ; similarly with the corolla only four sepals 

 and four petals are visible, but theoretically there are five 

 of each. 



Theoretical floral diagrams are of undoubted value in 

 morphological studies pursued with a requisite knowledge 

 of the actual existing state of affairs in living plants, but 

 the tendency in some modern text-books to place large 

 series of them before elementary students may easily lead 

 to confusion and misapprehensions. 



In order to aid in the practice of actually making 

 floral diagrams, however, the reader may compare the 

 following examples with the flowers they represent : 



Willow, Wallflower, Blackberry, Rose, Pear, Ivy, Elder, 

 Verbascum, Linaria, Veronica, Primula, Orchis (Fig. 32), 

 Ranunculus, (Fig. 33). 



Fig. 33. Inflorescence (axillary dichasial cyme) of Ranunculus acris 

 with details of central flower showing spiral arrangement. Stamens in 

 ^- phyllotaxy. a, , bracteoles of central flower, in the axil of each of 

 which arises a lateral flower with bracteoles a', /3' ; branching is repeated 

 in the axils of a', /3' (Ei). 



The exigencies of descriptive botany have also called 

 forth another way of expressing shortly such structural 

 arrangements in a kind of shorthand, so to speak. 



If we agree to accept the conventional letters K, C, 



