The floral formula and diagram article provides a study note on the floral formula and the floral diagram (labelled diagram).
The floral formula is a quick and easy way to describe a flower. In this equation, K is the calyx, C is the corolla, P is the perianth, A is the androccium, and G is the gynoecium. The number of members in a whorl is written next to the symbol for a whorl. The symbol ∞ means a large number that can’t be counted. If the members are in different whorls, the different whorls are written separately with a + sign between them.
A2+2 denotes an androecium with four stamens in two whorls of two each. The number is placed within the first brackets when members are united (cohesion). A line connecting the two whorls represents adhesion. A line below or above the gynoecium denotes its superior or inferior position. The male flower is represented by the symbol ♂, female flower by ♀ and hermaphrodite flower by ☿ or ⚥. The symmetry of the flower also may be signified by symbols like ꚛ for actinomorphic and ↓ for zygomorphic flowers. Thus
The floral diagram, which places the gynoecium in the centre and places the sepals, petals, and stamen in concentric circles (or spirals when the floral phyllotaxy is spiral), can sometimes make the ground plan of a flower very clear. In a floral diagram, the position of the inflorescence axis or stem is indicated by a dot or a small circle.
Thick initial brackets have come to be used to indicate petals (representing the t.s. of petals), sepals (showing the midrib), stamens (anthers), and carpels (placentation).
Straight lines can be used to represent the diagonal, lateral, or median planes. A second bracket may be used to display the brace. This makes it possible to clearly demonstrate the flower’s orientation and symmetry as well as that of its many parts. Connecting lines depict adhesion and cohesiveness.
The floral diagrams of a few common flowers are displayed to illustrate their structural details (Figure 2).
Figure 2: Floral Diagram of some common flowers.