Flowers

1. Flowers

2. Anthophyta
Division Anthophyta contains the flowering
plants, or Angiosperms. Flowering plants are
similar to non-flowering seed plants
(Gymnosperms) in having advanced vascular
tissue, a dominant sporophyte stage, a
markedly reduced gametophyte stage, and
production of seeds. Seeds are important
adaptations for terrestrial life because they
protect the sporophyte embryo from the
environment, they provide nutrients to the
embryo, and they can remain dormant during
stressful conditions.
Angiosperms differ from gymnosperms by
the production of a derived organ, the fruit.
Angiosperm ovules are enclosed in a carpel.
After fertilization, the ovule develops into the
seed and the carpel develops into the fruit.
Angiosperms also produce flowers, which are
structures containing the reproductive organs
of the sporophyte. The flower functions to
protect the gamete and to aid in dispersal of
male gametes (pollination) and fertilization of
eggs.

3. Introduction
• Receptacle = Place on stem where floral organs originate & attach
• Sepals = Lowest order of floral organs, first to develop, can be green & leaf-
like, Collectively = Calyx
• Petals = Inserted on the Receptacle just above the Sepals, usually brightly
colored, Collectively = Corolla
• Perianth = Collective term for Sepals + Petals
• Pistil- collective term for carpel(s). The terms CARPEL and PISTIL are
equivalent when there is no
• fusion, if fusion occurs then you have 2 or more CARPELS united into one
PISTIL.
• Stamen = Inserted above petals, consists of anther & filament, Collectively
= Androecium
• Anther - Part of stamen that produces pollen
• Filament - Stalk that bears the anther
• Carpel = Inserted above stamens, uppermost floral organ, consists of
stigma, style & ovary, Collectively = Gynoecium
• Stigma - Tip of the carpel, receptive to pollen
• Ovary - Base of the carpel, contains ovules
• Style - Connects the stigma to the ovary
• Adnation - Fusion of floral parts from different whorls.

5. Introduction
A flower can have four types of
specialized leaf whorls, the (1) calyx
and (2) corolla (sterile) as well as the
(3) androecium (microsporophylls) and
(4) gynoecium (megasporophylls). Most
flowers have all four, but in some cases,
one or more of the whorls has been
secondarily lost. A flower that has
• sepals
• petals
• stamens
• carpels
...is said to be a complete flower. A
flower that lacks one or more of these
whorls is said to be an incomplete
flower.

6. Floral Morphology
Flower parts include:
• Receptacle
• Peduncle
• Perianth
– sepals (calyx)
– petals (corolla)
• Androecium
– stamens
• filaments
• anthers
– pollen
– connective
• Gynoecium
– carpels
• ovary
• style
• stigma

7. Completeness
• Complete - Has all four floral
organs
• Incomplete - One or more
floral organs missing
• Perfect - Flower with
Androecium & Gynoecium
• Imperfect - Missing
Androecium OR Gynoecium
– staminate – has stamens only
– carpellate – has carpels only

8. Plant conditions
• Synoecious - when all the
flowers of an individual
contains both male and
female parts (the flowers
are perfect);
• Monoecious (one house) -
One plant has BOTH
carpellate & staminate
flowers;
• Dioecious (two houses)-
one plant has only
staminate flowers &
another plant has only
carpellate flowers.

9. Ovulary Position
• superior ovary
– hypogynous flower - other
floral organs attached below
the gynoecium on the
receptacle.
• half-inferior
– perigynous flower - sepals,
petals & stamens arise from a
tubular extension of the
receptacle called the
hypanthium which surrounds
the ovary but is NOT fused to
the ovary wall.
• inferior ovary
- epigynous - stamens, petals
& sepals appear to grow
from the top of the ovary

10. Female gametophyte

11. Inflorescences
Flowers may be borne singly, on a peduncle, or
in a cluster called an inflorescence. The tiny
stalk of an individual flower in an inflorescence
is called a pedicel.

12. Indeterminate Inflorescences
An indeterminate inflorescence has new buds growing at
the apex while mature flowers appear on lower pedicels.
Buds open first from the base of the inflorescence.

13. Determinate Inflorescences
A determinate inflorescence has new buds
growing at the base while mature flowers
appear on upper pedicels. Buds open first at the
top of the inflorescence.

14. Flower symmetry
In order to describe the shape of flowers, we
often speak of the symmetry of the flower. For
example, if one looks down at a buttercup
flower, with many whorls of petals, stamens and
carpels, you can dissect the flower into many
planes of symmetry (plane of symmetry =
bisecting an object into 2 mirror images).
Buttercups have radial symmetry.
If on the other hand, one looks at an orchid
flower, with its highly derived characteristics,
one can only find one plane of symmetry. This is
bilateral symmetry.
There are cases, such as in the mustard family,
where one commonly finds two planes of
symmetry, and this is biradial symmetry.
And there are cases where flowers are so
asymmetrical that there are no planes of
symmetry, and this is asymmetrical.

15. Pollination
It is often possible to determine what type of
pollination/pollinator a plant uses by the structure, color,
shape, and smell of the flower. You should be familiar
with this table:

16. Floral formulas and diagrams
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

17. Somewhere you can find these
symbols:

18. Floral formula

19. Floral Formula Symbol 1
The first symbol in a floral formula
describes the symmetry of a
flower.
• (* or ) Radial symmetry –
Divisible into equal halves by
two or more planes of
symmetry (actinomorphic
flower).
• (+) Bilateral symmetry –
Divisible into equal halves by
only one plane of symmetry.
• ($) Asymmetrical – Flower
lacking a plane of symmetry,
neither radial or bilateral.
• If there is only one plane of
symmetry, then the flower is
zygomorphic and is
represented by

20. 20
Floral Formula Symbol 2
The second major symbol in the floral formula is
the number of sepals, with “K” or “Ca”
representing “calyx”. Thus, K5 would mean a
calyx of five sepals.

21. 21
Floral Formula Symbol 3
The third symbol is the number of petals, with
“C” or “Co” representing “corolla”. Thus, C5
means a corolla of 5 petals.

22. 22
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.

23. 23
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.
• 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.

24. 24
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)

25. More examples

26. 26
More on Floral Formulas
Connation (like parts fused) is indicated by a
circle around the number representing the parts
involved. For example:

27. 27
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.

28. 28
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

29. 29
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
Sometimes instead of „T“ you can find „P“
which stands for perianth.

30. 30
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.

31. 31
Floral Diagram Symbols I

32. 32
Floral Diagram Symbols II

33. 33
Sample floral diagrams

34. More examples

35. More examples

36. And now let‘s practice

37. More practice

38. Sources
Big thanks to:
http://www.bio.miami.edu/dana/226/226F09_2
1.html
www.msubillings.edu
http://ashipunov.info/shipunov/school/biol_154
/2011_2012/lab_04.pdf
http://crescentok.com/staff/jaskew/ISR/botzo/d
iapractice.htm