Floral Formulas
Floral formulas are a short hand way of depicting the information about a flower. There are no official rules so there are many different systems. We will be using the system from Vascular Plant Families by James Payne Smith, with slight modifications to bring it in line with the terminology of the Jepson Manual. Here are links to those used at Texas A&M.
I. Symbols for the parts of a flower:
K = calyx
C = corolla
A = androecium (* = a staminode, sterile stamen)
G = gynoecium
a straight line below the G indicates a superior ovary, a straight line above the G indicates an inferior ovary, -G- indicates half inferior
&
are used to designate male and female flowers
II. Numbers of parts:
Superscript numbers are used to designate the numbers of each parts:
K5 = 5 free sepals
C0 = corolla is missing, no petals
x = variable number
∞ (infinity) = a high unstable number; over 20
numbers in brackets [ ] = sometimes or rarely, e.g. A4[5] means androecium usually 4 stamens, rarely 5
III. Fusion of parts:
IV. Symmetry - lower case subscripts are used with the calyx and corolla to indicate symmetry (I made these up to conform with the Jepson Manual terminology):Connation, fusion of like parts, is indicated by parentheses ()
C(5) = 5 fused petals
A(9)+1 = androecium of 10 stamens, 9 fused together, one free
Curved lines may be drawn above or below a number to indicate fused only at the top and fused only at the bottom, respectively
Adnation, fusion of unlike parts, is indicated by lines above or below for parts fused at the top and bottom, respectively
K C A indicates the calyx, corolla and androecium are united at their bases (hypanthium)
a = asymmetrical - irregular, not divisible into identical mirror image halves
bl = bilateral - divisible into mirror image halves in only one way
br = biradial - divisible into mirror image halves in two ways
r = radial - divisible into mirror image halves in three or more ways
Ka means the calyx is asymmetrical, KrCbl means the calyx is radial and the corolla is bilateral
V. An example: the formula below translates to a flower with a calyx of 5 separate sepals with radial symmetry; a bilateral corolla of 5 petals, 2 joined together, two forming a pair and a 5th different from the rest; androecium of 10 stamens, 9 joined by their filaments, the 10th free; gynoecium unicarpellate, the ovary superior.
