5 a. floral formulas and diagrams

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Floral Formulasand DiagramsBY: GHANSHYAM R. PARMAR

DEPARTMENT OF PHARMACY

SUMANDEEP VIDYAPEETH

VADODARA-391760

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Floral Formulas

and Diagrams

Convenient shorthand methods of recording floral

symmetry, number of parts, connation andadnation, insertion, and ovary position.

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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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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.

PetalLocated 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.

StamenMale 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.

PollenGrains containing the male gametes. Immature male gametophyte with a

protective outer covering.

Carpel\Pistil 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.

StyleThe stalk of a carpel, between the stigma and the ovary, through which the

pollen tube grows.

OvaryEnlarged base of the carpel containing the ovule or ovules. The ovary matures

to become a fruit.

OvuleLocated in the ovaries. Carries female gametes. Ovules become seeds on

fertilization.

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The sexof a flower can be described in three ways:

Staminate f lowers: Flowers bearing only male sex parts.

These are sometime referred to as "male flowers".

Carpellate\Pisti l late F lowers: Flowers bearing only

female sex parts. These are sometimes referred to as

"female flowers".

Hermaphhrodite\Complete f lowers: Flowers bearing

both male and female sex parts.

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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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Floral Formula Symbol 1

The first symbol in a floral formula describes thesymmetry of a flower.

(*) Radial symmetryDivisible into equal halvesby two or more planes of symmetry.

(x) Bilateral symmetryDivisible into equal halves

by only one plane of symmetry. ($) AsymmetricalFlower lacking a plane of

symmetry, neither radial or bilateral.

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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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The third symbol is the number of petals, with C

representing corolla. Thus, C5 means a corolla of 5

petals.

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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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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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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

At the end of the floral formula, the fruit type is often

listed.

Example:

*, K5, C5, A, G10, capsule

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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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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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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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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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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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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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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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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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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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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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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 26


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Floral Diagram Symbols II 27


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Sample floral diagrams 28


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Sample Floral Diagrams

Described 29

EVIDENCE BASED REFERENCE


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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 cansummarise a

wide range of

features,

including:

acropetal

sequence of

organ initiation,

number and

symmetry ofeach

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 differentontogenetic 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.

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