Floral Formulae
Formulae are useful in understanding the characteristics of different angiosperm
families.
A floral formula consists of five symbols indicating from left to right
1. Floral sex,
Sex of the individual flowers may be imperfect (ie with separate Male denoted
by ♂, or Female denoted by ♁) or perfect (ie hermaphrodite or bisexual
denoted by ⚤)
2. Floral Symmetry.
The first symbol in a floral formula describes the symmetry of a flower.
Actinomorphic = Radially symmetrical (✶) or Zygomorphic = Bilaterally
symmetrical (†). Some flowers may be asymmetrical (↯)
3. K Number of Sepals(calyx)
Thus, K5 means a calyx of 5 petals.
4. C Number of Petals(corolla)
Thus, C5 means a corolla of 5 petals.
5. P or Number of Tepals (Perianth) when you cannot see sepals or petals
Thus, P6 means a perianth of 6 petals. P3–12 – perianth from three to twelve
petals (when the number is variable between flowers).
6. A Number of Stamens.(Androecium)
Thus, A5 means am Androecium of 5 stamens. A10 would indicate 10
stamens, but A ∞ (the symbol for infinity) indicates numerous stamens and is
used when stamens number more than twelve in a flower.
7. G Number of Carpels in the ovary.(Gynoecium)
Thus, G10 means 10 carpels.
8. The position of the ovary (Gynoecium) may be above or below the floral parts
If above, it is called superior and is denoted by (–). The entire flower is thus
called hypogynous
If the ovary is below, it is called inferior and denoted by (_). These flowers
are also described as epigynous.
Some flowers have the sepals, petals and stamens fused together into a cup-
shaped structure called a hypanthium, obscuring the true position of the
ovary. The symbol for this sort of ovary would be through the middle (–).
These flowers are described as perigynous.
Note: The line denotes where the floral parts join. Thus (3) means 3 carpels
which are fused together and are superior (the floral parts joining below the
ovary and the ovary above the floral parts).
9. Whorls (+)
If parts are in separate whorls they are denoted by using an addition symbol
(+) so C 3+3 means 6 petals in two whorls of 3. K3+3 means 6 free sepals in
two whorls of 3.
10. Brackets are used to denote “fusion” of like parts (Connation)
Thus A(5) means five fused stamens. C(5) means 5 petals fused together.
11. Square brackets [ ] may be used to denote unlike parts fused (Adnation)
Thus [C(5)A5] – means the corolla has 5 petals fused to each other, which are
then also fused to 5 stamens. There are alternative ways to show this (ask
Mark)
Examples
⚤✶ P3+3 A3+3 G(3)
Liliaceae
Flowers are hermaphrodite and actinomorphic, with 6 tepals in two whorls of
three, 6 stamens again in two whorls of 3, and a superior ovary with 3 fused
carpels.
⚤ † K(5) C1 + 2 + (2) A(9) +1 G1
Fabaceae (Leguminosae)
Flowers are hermaphrodite and zygomorphic, with 5 sepals fused together, 5
petals (as 1 solitary, then 2, then 2 fused to each other), 9 stamens fused, and
a superior ovary with 1 carpel.
⚤ ✶ K(5) C5 A∞ G(1 – 5)
Rosaceae
Flowers are hermaphrodite and actinomorphic, with 5 sepals fused together, 5
petals (all free), many stamens all free, and an inferior ovary with 1 to 5 fused
carpels.
