CHAPTER XIV. 



FLORAL DIAGRAMS AND FLORAL FORMULA. 



Plan Diagrams of Buds Floral Diagrams Median, Lateral, and 

 Oblique Planes of Symmetry Cyclic flower Regular and 

 Actinomorphic Irregular and Zygomorphic Monosymmetri- 

 cal, Isobilateral, &c. Asymmetry Empirical and Theoretical 

 Diagrams Selected Types Conventional letters and signs 

 Floral Formulae Examples Buttercups Laburnum Bitter- 

 sweet Ericaceae Ob-diplostemony Polymorphic flowers 

 Cleistogamy Heterostylism Polygamy, &c. 



IT was shown in Volume I. pp. 41 48, that much 

 information regarding the relations between the parts of 

 a bud can be expressed in the form of plan diagrams, 

 based on transverse sections and comparative dissections 

 of the buds themselves, together with facts derived from 

 considerations of their development and alliances. 



Just as in the case of leaf-buds so with those of the 

 flower, it is possible to show very clearly on either actual 

 or theoretical diagrams many of the most important facts 

 of structure. Such diagrams are here termed floral 

 diagrams, and the art of constructing them has been 

 carried to great perfection, because the essential struc- 

 tural arrangements in the flower frequently correspond in 

 large groups of plants ; the systematic classification of 

 plants being, in fact, based chiefly on these very resem- 

 blances and differences. 



