Flower Parts
Ovary
Collectively the ovary, style and stigma make up the female parts of the
flower. This collection of female parts is called the pistil or gynoecium.
Stigma
Style
Pistil
Ovary
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Ovary
Stigmas
The ovary is the expanded
base of the pistil that will
contain the ovules.
The ovary is derived from one
to many carpels that enclose
the ovules.
Stamens
Styles
Petals
Sepals
Ovary
Kalanchoe
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Ovary
A carpel is the compartment
that bears the ovules (seeds).
A carpel evolved as a fertile
leaf (megasporophyll)
modified to house and
protect the ovules.
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Un-folded carpel
Partly-folded
Midrib
A carpel was established as
the result of this modified
leaf folding over and fusing
along one edge to form a
protective chamber.
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Hypothetical megasporophyll evolving as a folded and
fused carpel with ovules produced along one leaf edge.
Ovules
Midrib
Cross-sections
Fully-folded
Midrib
Megasporophyll
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Flower Parts
Ovary
Winter aconite (Eranthis) produces a flower with multiple independent carpels.
In the mature fruit (follicle), it is easy to envision how each carpel (fruit) is
derived from a folded modified leaf.
Ovules
(seeds)
Carpel
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Ovary
A single flower may have either a simple or compound pistil.
Flowers with simple pistils can have a single carpel (monocarpous)
or multiple independent carpels (apocarpous). Flowers with
compound pistils have multiple fused carpels (syncarpous).
Monocarpous
Single
simple
pistil
Baptisia
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Syncarpous
Apocarpous
A
compound
pistil with
fused
carpels
Multiple
simple
pistils
Rosa
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Note the
five styles
emerging
from the
ovary
Sopanaria
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Flower Parts
Ovary
Most legumes have a simple pistil and a single simple
carpel (monocarpous).
Baptisia
Pod longitudinal
section
Pod cross-section
Carpel
Single
simple
pistil
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Ovules
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Two
rows of
ovules
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Flower Parts
Ovary
Peony is a good example of a flower with a simple pistil and multiple individual
carpels (apocarpous).
Five
carpels
Simple
pistils
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Ovary
Citrus has a compound pistil with multiple fused carpels (syncarpous). There is
a mutation in Citrus called ‘Buddha's Hand’ that nicely shows the relationship
between having individual vs. fused carpels. The carpels in ‘Buddha’s Hand’ do
not completely fuse resulting in finger-like growth in the fruit.
Fused carpels
Carpel
Individual carpels
Buddha's Hand
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Ovary
In cross-section, the ovary contains one to many chambers (locules) that are
separated by ovary tissue called a septum. Many times the number of locules in
an ovary is the same as the number of carpels, but not always. Each ovule is
attached to part of the ovary called the placenta by the funiculus.
Ovary with fused three carpels
Locule
1
Funiculus
Ovary with five fused carpels
Septum
5
Ovules
Placenta
Locule
1
2
Ovules
Septum
3
Ovary
2
Lily (Lilium)
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Placenta
4
3
Ovary
Pitcher plant (Sarracenia)
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Ovary position
The position of the ovary is characteristic of different plant families. The
three types of ovary positions are called hypogynous, perigynous and epigynous
depending on whether the ovary is above the other flower parts, below the
flower parts or held up on a special structure called a hypanthium.
Sepals
Ovary
Hypogynous (Superior) – all
flower parts attached below
the ovary.
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Petals
Petals
Petals
Sepals
Stamens
Stamens
Stamens
Ovary
Epigynous (Inferior) – all
flower parts attached
above the ovary.
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Sepals
Hypanthium
Ovary
Perigynous (Intermediate) –
flower parts attached to
specialized tube (hypanthium).
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Ovary position
A hypogynous flower has a superior ovary that is above the other flower parts.
St. John’s wort is a good example of this type of ovary position.
Stamens
Petals
Ovary
Sepals
Hypogynous
(Superior)
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St. John’s wort (Hypericum)
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Ovary position
African violet (Saintpaulia) has an hypogynous flower with a superior ovary.
Petals
Petals
Stigma
Stigma
Style
Stamens
Stamens
Ovary
Attachment of floral
organs below the ovary
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Ovary
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Ovary position
An epigynous flower has an inferior ovary with the flower parts
above the ovary. Evening primrose and fuchsia nicely shows the
separation between the ovary and the other flower parts.
Stamens
Stamens
Petals
Epigynous
(Inferior)
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Fuschia (Fuschia)
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Evening primrose (Oenothera)
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Ovary position
Squash has an epigynous female flower with an inferior ovary.
Attachment of floral
organs above the ovary
Ovary
Petals
Stigma
Style
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Ovary position
A perigynous flower is characterized by having a receptacle cup (hypanthium)
that surrounds the ovary. The floral parts initiate from this cup.
Stamens
Petals
Sepals
Ovary
Hypanthium
Perigynous
(Intermediate)
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Flower in the bud
Open flower
Balloonflower (Platycodon)
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Ovary position
Petals
Rose has a perigynous
flower with many
independent, simple
pistils.
Note how the sepal,
petals, and stamens
attach at the rim of
the hypanthium and
the ovaries are
inserted down into the
cup formed by the
hypanthium.
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Sepals
Rim of
hypanthium
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Hypanthium
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Many simple
pistils
Ovaries
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Ovary position
A gynophore is an extension of the
receptacle (stalk) that raises the
pistil above the petal whorl.
In caper (Capparis), the receptacle
extension raises the pistil above
the petals and stamens.
Gynophore
Petals
Pistil
Pistil
Stamens
Gynophore
Receptacle
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Ovary position
Passionflower (Passiflora)
When the stamens and
pistil are raised above
the petals, the gynophore
(receptacle stalk) is
further differentiated as
an androgynophore.
Ovary
Stamens
Corona
Gynophore
Petals
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Sepals
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Petals
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Ovary placentation
Ovules are arranged in patterns within the ovary on placental connections.
There are five basic types of placentation –
Marginal, Basal, Axile, Parietal and Free central.
Basal
Marginal
Axile
Parietal
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Free central
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Marginal placentation
Marginal placentation occurs in ovaries that consist of a single separate
carpel. The ovules are attached to the ovary wall along one edge of the ovary.
Ovary
Ovule
Funiculus
Placenta
False indigo
(Baptisia pendula)
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Marginal placentation
In a developing peony fruit with marginal placentation, you can clearly see the
ovules attached in rows on the outer edge of the folded ovary. Also note that
there are no partitions in the ovary (a single carpel / locule).
Ovary
Ovule
Placenta
Peony (Paeonia officinalis)
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Marginal placentation
Columbine produces a fruit (aggregate of follicles) derived from numerous single
carpels. Each carpel has a single locule and shows a marginal placentation.
Seven
carpels
Placenta
Columbine
(Aquilegia)
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Ovary
Ovules
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Basal placentation
In basal placentation, a single ovule or multiple ovules are located at one end
of the ovary. The ovary is usually comprised of a single chamber (locule) but
may be derived from a single independent carpel or multiple fused carpels.
Ovary
Ovule
Avocado (Persea gratissima)
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Basal placentation
When the ovule is located at the pedicel (flower stalk) end of the
ovary it is termed erect and when the ovule is located at the opposite
end of the ovary it is termed pendulous.
Erect placentation
Pendulous placentation
Ovule
Pedicel
Linden (Tilia
tomentosa)
Pedicel
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Cherry
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Prunus cerasus
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Basal placentation
At first glance, many aggregate fruits appear to have free central or axial
placentation. However, aggregate fruits are actually groupings of attached
individual ovaries usually with a single ovule often with basal placentation.
Ovary
Ovule
Sweet gum (Liquidambar styricaflua)
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Sweet bay (Magnolia glabra)
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Parietal placentation
Parietal placentation occurs in an ovary with fused carpels (syncarpous) that has
ovules attached at multiple points (placenta) on the ovary wall.
Three carpels - One locule
Ovary
Ovules
Locule
Placental
attachment
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Parietal placentation
In chelondine poppy, three rows of ovules attach at three
locations on the ovary.
Ovary
1
3
Ovule
2
Placenta
Chelondine poppy
Stylophorum diphyllum
Ovule
Ovule
Aborted ovule
Placenta
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Parietal placentation
Cactus can appear to have a riot of ovules in the ovary because each is borne on a
long funiculus. If you look closely, you will see that the placentation is parietal.
Ovary
Placenta
Placenta
Funiculus
Ovule
Cactus (Echinopsis)
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Axile placentation
Axile placentation also occurs in ovaries with fused carpels (syncarpous).
Ovules are attached to a central axis (placenta) in an ovary with numerous
partitioned locules.
Three carpels – Three locules
Ovary
Ovule
Locule
Central axis
placenta
Day lily (Hemerocallis)
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Axile placentation
Below is a cross- and longitudinal-section of an un-open day lily
(Hemerocallis) flower showing an axile placentation.
Crosssection
Longitudinalsection
Petals
Ovary
Ovule
Longitudinalsection
Locule
Central axis
(placenta)
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Axile placentation
Ovaries with three locules in axile placentation are typical of monocots.
Amazon Lily
Lillium
Lily
Eucharis
Tulip
Tulipa
Iris
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Axile placentation
Foxglove is an example of an ovary with two fused carpels
and two locules with axile placentation.
Developing ovary
Nearly mature ovary
Foxglove (Digitalis)
Ovary
Locules
Ovule
Crosssections
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Longitudinalsection
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Axile placentation
Dicots with axile placentation can have two, or more locules within an ovary.
Six
locules
Two
locules
Love-in-a-mist
Nigella
Central
axis
Five
locules
Central
axis
Pitcher plant
(Sarracenia)
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Balloon flower
Platycodon
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Axile placentation
Blueberry shows the typical star-shape seen in many fleshy ovaries that will
become berries. The star-shape is created by the axile placentation but the
individual locules can be difficult to see in the fleshy fruit.
Blueberry (Vaccinium)
Ovary
Ovule
Central axis
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Axile placentation
In kiwi fruit, there is a high percentage of fertilized ovules with
many ovules per locule and many locules. In serviceberry, There are
only two ovules per locule and most of the ovules have aborted due to
lack of fertilization except for a pair in one locule.
Kiwi (Actinidia)
Serviceberry
(Amelanchier)
Aborted
Ovules
Ovary
Ovule
Central axis
Locule
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Parietal vs. Axile Placentation
The placenta in some ovaries can be elaborate and extend into the locule.
Although similar in appearance St. John’s wort ovaries have parietal
placentation and thorn apple has axile placentation.
Axile
Parietal
Ovary
Ovules
Placenta
St. John’s wort
(Hypericum)
Thorn apple
(Datura)
Ovary
Placenta
attached to
ovary wall.
Placenta
attached to
ovary central
axis.
Ovules
Placenta
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Free central placentation
In free central placentation, ovules are attached to a free-standing central
axis in an ovary with only a single locule but numerous fused carpels.
Ovary
Ovule
Central axis
Shooting star (Dodecatheon)
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Free central placentation
Shooting star has an ovary of five fused carpels as a single locule. Ovules
are produced just below the ovary wall. The central axis is considered
free standing because it does not attach at the top of the ovary.
Central axis
does not
attach to top
of the ovary
Ovary
Ovule
Central axis
Shooting star ( Dodecatheon)
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