Floral Formulas
A Cool Way to
Look at Floral
Anatomy
Floral Formulas
• System of notation
• Display a ton of
information about the
structure of a flower
– Similar to the notation
we used when we
learned about grasses
• Not standardized
Floral Formulas
• Using the 4 whorls of
floral parts as our
reference
–
–
–
–
Calyx (sepals)
Corolla (petals)
Androecium (stamens)
Gynoecium (pistils)
Floral Formulas
•
•
•
•
K = calyx
C = corolla
A = androecium
G = gynoecium
Floral Formulas
Number of Parts
•
•
•
•
•
•
K5 = calyx of 5 sepals
C6 = corolla of 6 petals
A10 = androecium of 10 stamens
G2 = gynoecium of 2 carpels
C0 = corolla missing
A4[5] = androecium usually of 4 stamens, rarely 5
Floral Formulas
Number of Parts (a little more complicated)
• A4+2 = androecium of 6 stamens, 4 in 1 set, 2 in
another
• G2-3 = gynoecium of 2 or 3 carpel
• Ax = androecium of a low unstable number (about
10-20) stamens
• G∞ = gynoecium of high unstable number, more than
20 carpels
Floral Formulas
Symmetry
•
•
•
•
K = calyx actinomorphic (radially)
C = corolla actinomorphic
Kz = calyx zygomorphic (bilaterally)
Cz = corolla zygomorphic
Floral Formulas
Fusion of Parts
•
•
•
•
•
•
K4 = calyx of 4 separate sepals
C3 = corolla of 3 separate petals
K(4) = calyx of 4 fused sepals
G(2) = gynoecium of 2 fused carpels
G4 = gynoecium of 4 separate carpels
A5 = androecium of 5 stamens fused by their
filaments
Floral Formulas
Fusion of Parts (cont.)
• A5G2 = androecium and gynoecium fused by
their upper parts
• K C A = calyx, corolla, and androecium united
into a hypanthium
Floral Formulas
Ovary Position
•
•
•
•
G = ovary superior; flower hypogenous or perigynous
G = ovary inferior; flower epigynous
-G- = ovary half-inferior
G = ovary either superior or inferior
Floral Formulas
Given:
5
1+(2)+2
9+1
1
K Cz
A G
Floral Formulas
Translation
K5 Cz1+(2)+2 A9 +1 G1
• Calyx of 5 separate sepals
• Corolla zygomorphic (bilaterally symmetrical); of 5
petals, 2 fused together, 2 free and forming a pair,
and a 5th different from the others
• Androecium of 10 stamens, 9 joined by their
filaments, the 10th free
• Gynoecium unicarpellate, the ovary superior
Interpreting Floral Formulas
Practice
(5)
K
(5)
2
or
2+2
(2)
Cz A
G
Interpreting Floral Formulas
Practice
3-5
K
5
∞
(5-8)
C A G
Interpreting Floral Formulas
Practice
4
K
4
4+2
(2)
C A G
Interpreting Floral Formulas
Practice
4
K
4
8
(4)
C A G
Interpreting Floral Formulas
Practice
(5)
K
(5)
5
(2)
C A G
Interpreting Floral Formulas
Practice
(5)
K
5
2+2
(2)
Cz A G
Writing Floral Formulas
Practice
• Given the following description, write the
floral formula:
• Flowers bilaterally symmetrical
• 5 fused sepals
• 5 fused petals
• 4 stamens, 2 in one set and 2 in another
• Superior ovary, 2 fused carpels
Writing Floral Formulas
Practice
• Given the following description, write the
floral formula:
• 4 sepals
• 4 petals
• 8 stamen
• Calyx, corolla, androecium form a hypanthium
• Inferior ovary, 4 fused carpels
Writing Floral Formulas
Practice
• Given the following description, write the
floral formula:
• 3-5 fused sepals
• 5 petals
• More than 20 fused stamens
• Superior ovary, 5-8 fused carpels
Writing Floral Formulas
Practice
• Given the following description, write the
floral formula:
• 5 fused sepals
• 5 petals
• 10-many stamens, sometimes 4
• Superior ovary, 1 carpel
Writing Floral Formulas
Practice
• Given the following description, write the
floral formula:
• 5 fused sepals
• 5 petals, zygomorphic
• 10 stamens
• Superior ovary, 1 carpel
Writing Floral Formulas
Practice
• Given the following description, write the
floral formula:
• 4-5 fused sepals
• 4-5 fused petals, zygomorphic
• 4 stamens in 2 sets of 2
• Hypogenous, 2 fused carpels
Homework For Next Time
• Using your notes from previous classes, try to
figure out which plant families you have just
written the floral formulas for
• Bring the names of the families with you to
our next meeting