Q.Describe the arrangement of floral members in relation to their insertion on thalamus.
🔒You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.
🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Ovary Position And Flower Symmetry
Ovary Position and Flower Symmetry
Where is the ovary, and why does it matter?
Imagine a flower as a set of rings stacked on a stem. The outermost ring is the calyx (sepals), then the corolla (petals), then the androecium (stamens), and finally, at the very centre, the gynoecium (the ovary, style, and stigma). The key question is: where exactly do the sepals, petals, and stamens attach relative to the ovary?
That attachment point determines whether the ovary is superior (sits above everything else) or inferior (sunk below the attachment of the other floral parts). This is not a trivial detail — it affects how the flower looks, how it is pollinated, and even what kind of fruit it will form.
The three ovary positions
1. Hypogynous flower — superior ovary
The word breaks into hypo (below) and gynoecium (female part). The sepals, petals, and stamens are attached below the ovary. The ovary sits at the highest point of the receptacle.
Think of a cup with the ovary resting on top like a ball. The other floral parts arise from the rim of the cup, below the ball.
The ovary is called superior. Examples: mustard, brinjal (eggplant), China rose, and most common flowers like hibiscus.
2. Perigynous flower — half-inferior ovary
Peri means around. Here, the receptacle is slightly cup-shaped, and the ovary sits in the middle of the cup. The sepals, petals, and stamens are attached around the ovary, at the same level as the ovary's base — not below it, not above it.
The ovary is still technically superior in many textbooks, but it is often called half-inferior because the floral parts surround it at the same height. The key visual: the ovary is not raised above the attachment point.
Examples: rose, peach, plum (all members of the Rosaceae family).
3. Epigynous flower — inferior ovary
Epi means upon. The receptacle is fused to the ovary wall, and the sepals, petals, and stamens appear to arise from the top of the ovary. The ovary is completely inferior — it is embedded in the receptacle, and the other floral parts sit above it.
A common mistake: thinking the ovary is "below" the petals. It is not — the ovary is inside the receptacle, and the petals attach at its top. The ovary is inferior because its base is below the attachment of the other whorls.
Examples: apple, cucumber, sunflower (the "flower" of a sunflower is actually a head of many tiny flowers, each with an inferior ovary).
Flower symmetry: actinomorphic vs. zygomorphic
Now that you know where the ovary sits, look at the overall shape of the flower. If you draw a line through the centre, how many planes of symmetry does the flower have?
Actinomorphic (radial symmetry)
The flower can be divided into two identical halves by any vertical plane passing through the centre. It is like a star — many lines of symmetry.
Actinomorphic = regular, radially symmetrical.
Example: mustard, hibiscus, tulip.
Zygomorphic (bilateral symmetry)
The flower can be divided into two identical halves by only one specific vertical plane. It is like a face — only one line of symmetry (left-right).
Zygomorphic = irregular, bilaterally symmetrical.
Example: pea, bean, orchids, snapdragon.
Putting it together: why both matter
In exam questions, you will often be asked to classify a flower by both ovary position and symmetry. For instance:
- Mustard: hypogynous (superior ovary) + actinomorphic.
- Pea: perigynous (half-inferior) + zygomorphic.
- Apple: epigynous (inferior ovary) + actinomorphic. …
Based on how the other floral whorls sit relative to the ovary on the thalamus, flowers are hypogynous (superior ovary), perigynous (half-inferior), or epigynous (inferior ovary).
The arrangement of the floral whorls (calyx, corolla, androecium) with respect to the ovary on the thalamus gives three conditions:
- Hypogynous flower: The gynoecium (ovary) is at the highest position, and the sepals, petals and stamens are borne below it. Here the ovary is superior. Examples: mustard, china rose, brinjal.
- Perigynous flower: The gynoecium is at the centre and the other whorls are borne on the rim of a cup-shaped thalamus, roughly at the same level as the ovary. Here the ovary is said to be half-inferior. Examples: rose, plum, peach. …
- CBSE 2026Set ANNUAL1 markMCQQ.Flowers of which of the following plants are zygomorphic?(a) Mustard(b) Datura(c) Chilli(d) Gulmohar
›Reveal solutionSolution
Gulmohar flowers show zygomorphic (bilateral) symmetry, unlike the actinomorphic flowers of mustard, datura and chilli.
Flower symmetry is described as actinomorphic when the flower can be divided into two equal radial halves in any vertical plane passing through the centre (radial symmetry) — this is seen in mustard, datura, and chilli. A flower is described as zygomorphic when it can be divided into two similar (mirror-image) halves in only ONE particular vertical plane — this bilateral symmetry is a feature of flowers such as pea, bean, and Gulmohar (Delonix regia), whose petals are unequal in size/shape, producing an irr …
- CBSE 2025Set ANNUAL1 markMCQQ.Inferior ovary is found in flower of :(a) Guava(b) Mustard(c) China rose(d) Brinjal
›Reveal solutionSolution
Guava has an inferior ovary (epigynous condition); mustard, China rose and brinjal all have a superior ovary.
The position of the ovary relative to the other floral parts (calyx, corolla, androecium) on the thalamus gives three conditions:
- Hypogynous (ovary superior): ovary sits above the other whorls, which are attached below it — seen in mustard, China rose (Hibiscus), and brinjal.
- Perigynous (ovary half-inferior): ovary sits in the middle, with the other whorls arising at roughly the same level — e.g. plum, rose. …
- CBSE 2024Set ANNUAL1 markMCQQ.In which of the following ovary is inferior ?(a) Mustard(b) Brinjal(c) China-rose(d) Guava
›Reveal solutionSolution
Guava flowers are epigynous, meaning the ovary is inferior — located below the point of attachment of the other floral parts.
Based on the position of the ovary in relation to other floral parts, flowers are classified as hypogynous (ovary superior — e.g., mustard, brinjal, china-rose, where the gynoecium is the highest and other floral parts are borne below it), perigynous (ovary half-inferior — e.g., plum, rose), and epigynous (ovary inferior — the calyx, corolla and androecium are borne above …
- CBSE 2024Set botany-hz1 markMCQQ.A flower which can be divided in two similar halves, only in one vertical plane is called :(a) Actinomorphic(b) Zygomorphic(c) Heteromorphic(d) None of these
›Reveal solutionSolution
A flower divisible into two equal halves along only one vertical plane is bilaterally symmetrical, and this is called zygomorphic (e.g. pea, gulmohar, bean flowers).
Flower symmetry is one of the standard characters used in floral description.
- Actinomorphic (radial symmetry): the flower can be divided into two identical halves along ANY vertical plane passing through the centre — e.g. mustard, datura, chilli flowers.
- Zygomorphic (bilateral symmetry): the flower can be divided into two identical halves along only ONE particular vertical plane — e.g. pea, bean, gulmohar, cassia flowers. …
- CBSE 2021Set ANNUAL1 markMCQQ.The ovary of which flowers is superior?(a) China rose(b) Mustard(c) Both (A) & (B)(d) Cucumber
›Reveal solutionSolution
China rose and Mustard are both hypogynous flowers with a superior ovary; Cucumber, an epigynous cucurbit flower, has an inferior ovary.
The position of the ovary relative to the other floral parts depends on the position of the thalamus (receptacle). In a hypogynous flower, the gynoecium occupies the highest position on a raised thalamus, and the ovary is described as superior — all other floral parts (calyx, corolla, androecium) are inserted below it. Both China rose (Hibiscus) and Mustard are hypogynous flowers with a superior ovary. Cucumber, being a …
- CBSE 2021Set ANNUAL1 markQ.What is zygomorphic flower?
›Reveal solutionSolution
Zygomorphic = bilaterally symmetrical flower, divisible into equal halves along only one plane.
Floral symmetry describes how a flower can be divided into equal halves. A zygomorphic flower is one that can be divided into two similar (mirror-image) halves only along one particular vertical plane, showing bilateral symmetry. Examples include pea, gulmohar, bean and Cassia. This is in contrast to an actinomorphic flower (e.g. mustard, Datura), which can be divided into …
- CBSE 2021Set ANNUAL1 markQ.What is perigynous flower?
›Reveal solutionSolution
In a perigynous flower, the thalamus is cup-shaped, the ovary sits in the middle at the same level as the other floral parts, and the ovary is half-inferior.
Perigyny is an intermediate condition of ovary position. The thalamus grows up in a cup-like shape around the gynoecium, but is not fused to it. The gynoecium is thus situated in the centre while the other floral parts — calyx, corolla and androecium — are borne on the rim of the cup-shaped thalamus at roughly the same level as the ovary. This gives the ovary a 'hal …
🎓Unlock everything free for 14 days
- ✓Full step-by-step solutions
- ✓Concept-first explanations
- ✓Methods, shortcuts & mistakes
- ✓PYQ mapping + timed mock tests
Full access for 14 days. No credit card required.