A method of recording floral structure by a series of symbols, letters, and numbers. The formula begins either with the sign
, representing actinomorphy, or with ·|· or ↑, representing zygomorphy. This is followed by a series of letters in the order Κ (for calyx), C (for corolla), A (for androecium) and G (for gynoecium). The number of parts (sepals, petals, stamens, and carpels respectively) in each whorl is given by a number following the appropriate letter. If this number exceeds 12 the symbol ∞ (infinity) is used. If the parts are fused then the number is bracketed. If the parts are in distinct whorls or groups this is indicated by splitting the number appropriately. Thus in the garden pea (Pisum sativum) there are ten stamens, nine of which are fused and the tenth separate. This is represented A(9) + 1. If two whorls are united then the representative symbols are joined by a single bracket. Thus in the primrose (Primula vulgaris) the stamens are inserted on the corolla tube. This is represented
If the sepals and petals are indistinguishable then Κ and C are replaced by Ρ representing perianth. The position of the ovary is indicated by a line, which in a superior ovary is placed beneath the number of carpels and in an inferior ovary above. Examples of floral formulae are
K4 C4 A4 + 2 G(2
) for the wallflower (Cheiranthus cheiri) and
P3 + 3 A3 + 3 G(3
) for the tulip (Tulipa species). Floral formulae are often accompanied by floral diagrams.