Floral formula basics

1. Floral Formulas
and Diagrams
BY: GHANSHYAM R. PARMAR
DEPARTMENT OF PHARMACY
SUMANDEEP VIDYAPEETH
VADODARA-391760
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2. Floral Formulas
and Diagrams
Convenient shorthand methods of recording floral
symmetry, number of parts, connation and
adnation, insertion, and ovary position.
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3. Floral Formulas
• A floral formula consists of five symbols indicating from
left to right:
• Floral Symmetry
• Number of Sepals
• Number of Petals
• Number of Stamens
• Number of Carpels
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5. Flower Part Form and Function
Peduncle Flower stalk.
Receptacle Part of flower stalk bearing the floral organs, at base of flower.
Sepal Leaf-like structures at flower base, protects young flower bud.
Calyx All the sepals together form the calyx.
Petal
Located in and above the sepals, often large and colourful, sometimes scented,
sometimes producing nectar. Often serve to attract pollinators to the plant.
Corolla All the petals together form the corolla.
Stamen
Male part of the flower, consisting of the anther and filament, makes pollen
grains.
Filament The stalk of the stamen which bears the anther.
Anther The pollen bearing portion of a stamen.
Pollen
Grains containing the male gametes. Immature male gametophyte with a
protective outer covering.
CarpelPistil Female part of the flower. Consisting of the stigma, style and ovary.
Stigma Often sticky top of carpel, serves as a receptive surface for pollen grains.
Style
The stalk of a carpel, between the stigma and the ovary, through which the
pollen tube grows.
Ovary
Enlarged base of the carpel containing the ovule or ovules. The ovary matures
to become a fruit.
Ovule
Located in the ovaries. Carries female gametes. Ovules become seeds on
fertilization.
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6. • The sex of a flower can be described in three ways:
• Staminate flowers: Flowers bearing only male sex parts.
These are sometime referred to as "male flowers".
• CarpellatePistillate Flowers: Flowers bearing only
female sex parts. These are sometimes referred to as
"female flowers".
• HermaphhroditeComplete flowers: Flowers bearing
both male and female sex parts.
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7. Floral Formulas
• Floral formulas 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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8. 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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9. 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.
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10. 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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11. 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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12. 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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13. 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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14. Floral Formulas
• At the end of the floral formula, the fruit type is often
listed.
• Example:
• *, K5, C5, A∞, G10, capsule
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15. More on Floral Formulas
• Connation (like parts fused) is indicated by a circle around the
number representing the parts involved. For example, in a
flower with 5 stamens all fused (connate) by their filaments,
the floral formula representation would be:
A 5
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16. More on Floral Formulas
• The plus symbol (+) is used to indicate differentation
among the members of any floral part. For example, a
flower with five large stamens alternating with five small
ones would be recorded as:
• A5 + 5.
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17. More on Floral Formulas
• Adnation (fusion of unlike parts) in indicated by a line
connecting the numbers representing different floral
parts. Thus, a flower that has 4 fused petals (connate
corolla) with 2 stamens fused (or adnate) to this corrola,
is described as:
• C 4 , A 2
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18. More on Floral Formulas
• The presence of a hypanthium (flat, cuplike, or tubular
structure on which the sepals, petals, and stamens are
borne usually formed from the fused bases of the perianth
parts and stamens) is indicated in the same fashion as
adnation:
• X, K 5, C 5, A 10, G 5
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19. More on Floral Formulas
• Sterile stamens or sterile carpels can be indicated by
placing a dot next to the number of these sterile
structures. Thus, a flower with a fused (syncarpous)
gynoecium composed of five fertile carpels and five
sterile carpels would be represented as:
• G 5 + 5
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20. More on Floral Formulas
• Variation in the number of floral parts within a taxon is
indicated by using a dash (-) to separate the minimum and
maximum numbers. For example a taxon that has flowers
with either 4 or 5 sepals would be indicated as:
• K 4-5
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21. More on Floral Formulas
• Variation with a taxon in either connation or adnation is
indicated by using a dashed (instead of continuous) line:
• C 3, A 6
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22. More on Floral Formulas
• The lack of a particular floral part is indicated by placing
a zero (0) in the appropriate position in the floral formula.
For example, a carpellate flower (flower with a
gynoecium but no functional androecium) would be
described as:
• *, K3, C3, A0, G2
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23. More on Floral Formulas
• Flowers with a perianth of tepals (no differentation
between calyx and corolla) have the second and third
symbols combined into one. A hyphen(-) is placed before
and after the number in this symbol. Example:
• *, T-5-, A 10, G 3
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24. More on Floral Formulas
• A line below the carpel number indicates the superior
position of the ovary with respect to other floral parts.
G3
• A line above the carpel number indicates the inferior
position of the ovary with respect to other floral parts.
G3
•
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25. 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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26. Floral Diagram Symbols I 26

27. Floral Diagram Symbols II 27

28. Sample floral diagrams 28

29. Sample Floral Diagrams
Described 29

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EVIDENCE BASED REFERENCE
Title/ Journal Author name Question Methodology Result conclusion
“Floral formulae
updated for
routine inclusion
in formal
taxonomic
descriptions“.
Taxon
Gerhard Prenner,
Richard M.
Bateman
Paula J. Rudall
2010; 59(1): 241-
250.
How to draw
floral formula
and floral
diagram?
Using standard
typeface and
Unicode
character codes,
the
format can
summarise a
wide range of
features,
including:
acropetal
sequence of
organ initiation,
number and
symmetry of
each
whorl of floral
organs (bracts,
sepals, petals
[or tepals],
androecium,
gynoecium,
ovules).
They can usefully be
applied within as well as
between
species, to compare wild
type versus mutant
morphs and different
ontogenetic stages.
Perhaps their greatest
strengths are that
they (1) require only a
universally available
typescript, and (2) bring a
comprehensive
uniformity to the
description of flowers,
acting as a checklist of
features to be examined.
It is recommend that
floral formulae become
a routine component of
diagnoses
in protologues and
other formal taxonomic
(re)descriptions,
functioning as a logical
phenotypic counterpart
to the DNA barcode.