Floral Formulas and Floral
Diagrams
Floral Formulas
Floral formula is a means to
represent the structure of a
flower using numbers, letters
and various symbols. A floral
formula is a compact form of
summarizing information about
the flower and its anatomy
Floral Diagrams
Floral diagrams are stylized cross
sections of flowers that represent
the floral whorls as viewed from
above. Rather like floral formulas,
floral diagrams are used to show
symmetry, numbers of parts, the
relationships of the parts to one
another, and degree of connation
and/or adnation. Such diagrams
cannot easily show ovary position.
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Floral Formulas
Floral formulae were developed in early 19th century
and used for the first time on a textbook by to describe
characteristics of floral families.
Sachs (1873) used them together with floral diagrams,
he noted their advantage of being composed of
"ordinary typeface".
Organogenesis of Flowers (1973) takes advantage of
floral formulae and diagrams to describe the ontogeny
of 50 plant species (embryonic development).
.
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Floral Formulas
Modern textbooks use floral formulae as a
descriptive. Floral formulas (formulae) are
useful tools for remembering characteristics
of the various angiosperm families. Their
construction requires careful observation of
individual flowers and of variation among the
flowers of the same or different individuals.
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Floral Formula Symbol 1
The first symbol in a floral formula describes the
symmetry of a flower.
(*) Radial symmetry – Divisible into equal halves by
two or more planes of symmetry.
(x) Bilateral symmetry – Divisible into equal halves
by only one plane of symmetry.
($) Asymmetrical – Flower lacking a plane of
symmetry, neither radial or bilateral.
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Floral symmetry
Floral Formula Symbol 2
The second major symbol in the floral formula is the
number of sepals, with “K” representing “calyx”.
Thus, K5 would mean a calyx of five sepals.
Floral Formula Symbol 3
The third symbol is the number of petals, with “C”
representing “corolla”. Thus, C5 means a corolla of
5 petals.
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Floral Formula Symbol 4
The fourth symbol in the floral
formula is the number of
stamens (androecial items),
with “A” representing
“androecium”. A∞ (the symbol
for infinity) indicates numerous
stamens and is used when
stamens number more than
twelve in a flower. A10 would
indicate 10 stamens.
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Floral Formula Symbol 5
The fifth symbol in a floral
formula indicates the number
of carpels, with “G”
representing “gynoecium”.
Thus, G10 would describe a
gynoecium of ten carpels.
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Floral Formulas
Using the 4 whorls of floral parts as our
reference
Calyx (sepals) = K
Corolla (petals)= C
Androecium (stamens) = A
Gynoecium (pistils) =G
Basic Floral Formula
*, K5, C5, A∞, G10
Radial symmetry= *,
5 sepals in the calyx= K5
5 petals in the corolla =C5
Numerous (12 or more) stamens = A∞
10 carpels = G10
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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
Symmetry
K = calyx actinomorphic (radially)
C = corolla actinomorphic
Kz = calyx zygomorphic (bilaterally)
Cz = corolla zygomorphic
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 1020) stamens
G∞ = gynoecium of high unstable number, more than 20
carpels
Floral Formulas
Fusion of Parts (Connation): is indicated by a circle
around the number or the number inside
parentheses. The number represents the the parts
involved.
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
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
A line below the carpel number indicates the
superior position of the ovary with respect to other
floral parts.
A line above the carpel number indicates the
inferior position of the ovary with respect to other
floral parts.
G = ovary superior
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
K5 Cz1+(2)+2 A9 +1 G1
Translation
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
Floral Diagrams
Floral diagrams are stylized cross sections of flowers
that represent the floral whorls as viewed from
above. Rather like floral formulas, floral diagrams
are used to show symmetry, numbers of parts, the
relationships of the parts to one another, and
degree of connation and/or adnation. Such
diagrams cannot easily show ovary position.
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Floral Diagram Symbols I
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Floral Diagram Symbols II
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Sample floral diagrams
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Sample Floral Diagrams Described
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