Breeding and Seed Production of Ornamental Crops (2+1)

Exercise - 6

Aim: To study the preparation of floral diagram and floral formula.
Material Required: Forceps, Needle, Scissors, pencil, eraser.
Floral Diagram:
The number of parts of a flower, their general structure, arrangement, aestivation, adhesion, cohesion and position with respect to the mother axis may be represented by a diagram known as the floral diagram. The floral diagram is the ground plan of a flower. In the diagram the calyx lies outermost, the corolla internal to the calyx, the androecium in the middle, and the gynoecium in the centre. Adhesion and cohesion of members of floral whorls may also be shown by connecting the respective parts with lines; for example, fig 1 shows that there are altogether ten stamens, of which nine are united into one bundle (cohesion) and the remaining one is free; while fig 2 shows that petals and stamens are united (adhesion). The black dot on the top represents the position of the mother axis (not the pedicel) which bears the flower. The axis lies behind the flower and, the side of the flower nearest the axis is called the posterior side, and the other side away from the axis the anterior side. The floral characteristics of a species may be well represented by a floral diagram, while to represent a genus or a family more than one diagram may be necessary.
Floral formula:
The different whorls of a flower, their number, cohesion, adhesion and their relative position may be represented by a formula known as floral formula. In the floral formula K stands for calyx, C for corolla, P for perianth, A for androecium, and G for gynoecium. The figures following the letters K, C, P, A and G indicate the number of parts of those whorls. Cohesion of a whorl is shown by enclosing the figure within the brackets, and adhesion is shown by a line drawn on the top of the two whorls concerned. In the case of the gynoecium the position of the ovary is shown by a line drawn above or below G or the figure. If the ovary is superior the line should be below it, and if it is inferior the line should be on the top. Thus all the parts of a flower may be represented in a general way by the floral formula; the flral characters of a family may be represented by one or more formulae. Besides, certain symbols are used to represent some particular features of flowers; thus♂ represents male, ♀ represents female, ♀ represents bisexual, О regular, •|• zygomorphic, ∞ indefinite etc.