What is the difference between racemose and cymose inflorescence?

In racemose inflorescence, the main axis grows indefinitely and flowers are borne in acropetal order (oldest at base, youngest at tip). In cymose inflorescence, the main axis terminates in a flower and growth is limited; flowers are borne in basipetal order (oldest at tip, youngest at base).

What is the structure of a dicot seed?

A dicot seed consists of a seed coat (testa + tegmen) enclosing the embryo. The embryo has two cotyledons, a plumule (future shoot), and a radicle (future root). In some seeds, endosperm is present (albuminous); in others, it is absent (exalbuminous) and food is stored in cotyledons.

What is the difference between a true fruit and a false fruit?

A true fruit develops only from the ovary after fertilisation (e.g., mango, tomato). A false fruit (pseudocarp) develops from parts other than the ovary — in apple and strawberry, the fleshy part develops from the thalamus, not the ovary.

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How to Use This Page

Solve each Samacheer Kalvi exercise question on your own first, then compare your answer with the solutions below. Reproductive Morphology covers flower structure, inflorescence types, fruit and seed — focus on identifying parts and their functions.

Key Concepts (Quick Recap)

Flower Structure

A typical flower has four whorls arranged on the thalamus:

1. Calyx (Sepals): Outermost whorl, green, protects the flower bud 2. Corolla (Petals): Second whorl, brightly coloured, attracts pollinators 3. Androecium (Stamens): Male reproductive whorl — each stamen has filament + anther 4. Gynoecium (Pistil/Carpel): Female reproductive whorl — each pistil has stigma + style + ovary

Types of Flowers

Feature	Type 1	Type 2
Based on floral parts	Complete (all 4 whorls)	Incomplete (one or more whorls missing)
Based on sex	Bisexual (both stamens and pistil)	Unisexual (only stamens or only pistil)
Based on symmetry	Actinomorphic (radial symmetry)	Zygomorphic (bilateral symmetry)
Based on ovary position	Hypogynous (ovary superior)	Epigynous (ovary inferior)
Based on bracts	Bracteate (with bracts)	Ebracteate (without bracts)

Aestivation (arrangement of petals/sepals in bud)

Valvate: Margins touch but don't overlap — e.g., Calotropis
Twisted: Margins overlap in one direction — e.g., Hibiscus, Cotton
Imbricate: Margins overlap irregularly — e.g., Cassia, Gulmohar
Vexillary (Papilionaceous): Largest petal (standard) overlaps the wings — e.g., Pea, Bean

Placentation (arrangement of ovules in ovary)

Marginal: Ovules along the ventral suture — e.g., Pea, Bean
Axile: Ovules on the central axis in a multilocular ovary — e.g., Tomato, Lily
Parietal: Ovules on the inner wall of the ovary — e.g., Mustard, Argemone
Basal: Single ovule at the base — e.g., Sunflower, Marigold
Free central: Ovules on the central axis without septa — e.g., Dianthus, Primrose

Inflorescence Types

Racemose: Main axis grows indefinitely; flowers in acropetal order
Raceme, Spike, Catkin, Spadix, Corymb, Umbel, Capitulum (head)
Cymose: Main axis terminates in a flower; flowers in basipetal order
Uniparous cyme, Biparous cyme, Multiparous cyme
Special types: Cyathium (Euphorbia), Verticillaster (Ocimum), Hypanthodium (Fig)

Fruit Types

True fruit: Develops only from the ovary — e.g., Mango, Tomato
False fruit (Pseudocarp): Develops from parts other than ovary — e.g., Apple (thalamus), Strawberry (thalamus)
Simple fleshy fruits: Drupe (mango), Berry (tomato, banana), Pome (apple)
Simple dry fruits: Achene (sunflower), Caryopsis (wheat), Cypsela (marigold), Legume (pea), Capsule (cotton)

Seed Structure

Dicot Seed (e.g., Bean):

Seed coat: Testa (outer) + Tegmen (inner)
Hilum: Scar where seed was attached to fruit
Micropyle: Small pore for water absorption
Embryo: Two cotyledons + Plumule (shoot) + Radicle (root)
Endosperm: Present (albuminous) or absent (exalbuminous)

Monocot Seed (e.g., Maize):

Seed coat: Fused with fruit wall (pericarp)
Endosperm: Large, starchy (albuminous)
Embryo: One cotyledon (scutellum) + Plumule + Radicle
Aleurone layer: Protein-rich outer layer of endosperm

I. Choose the Best Answer (MCQs)

Q1. The outermost whorl of a flower is called (a) Corolla (b) Androecium (c) Calyx (d) Gynoecium

Answer(c) Calyx — The calyx (sepals) is the outermost whorl of a flower. It protects the flower bud before it opens.

Q2. A flower having both stamens and pistil is called (a) Staminate (b) Pistillate (c) Bisexual (d) Neuter

Answer(c) Bisexual — A bisexual (hermaphrodite) flower has both male (stamens) and female (pistil) reproductive organs. Staminate = only stamens, Pistillate = only pistil, Neuter = neither.

Q3. In racemose inflorescence, the main axis (a) Terminates in a flower (b) Grows indefinitely (c) Grows from the centre (d) Branches repeatedly

Answer(b) Grows indefinitely — In racemose inflorescence, the main axis continues to grow and produces flowers laterally. The flowers are arranged in acropetal order (oldest at the base, youngest at the tip).

Q4. Apple is a (a) True fruit (b) False fruit (c) Aggregate fruit (d) Multiple fruit

Answer(b) False fruit — In apple, the fleshy, edible part develops from the thalamus (not from the ovary). The actual fruit (core) develops from the ovary. Hence, apple is a false fruit (pseudocarp).

Q5. The plumule of a seed develops into (a) Root (b) Stem (c) Leaf (d) Fruit

Answer(b) Stem — The plumule is the embryonic shoot that develops into the stem. The radicle develops into the root.

II. Fill in the Blanks

1. The four whorls of a flower are calyx, corolla, androecium, and gynoecium. 2. The male reproductive part of a flower is the androecium (stamen). 3. The female reproductive part of a flower is the gynoecium (pistil/carpel). 4. A flower with all four whorls is called a complete flower. 5. A flower with only stamens or only pistil is called a unisexual flower. 6. In racemose inflorescence, flowers are arranged in acropetal order. 7. In cymose inflorescence, flowers are arranged in basipetal order. 8. A true fruit develops from the ovary. 9. A false fruit develops from parts other than the ovary, such as the thalamus. 10. The seed coat has two layers: outer testa and inner tegmen. 11. The scar on the seed where it was attached to the fruit is called the hilum. 12. The small pore on the seed for water absorption is the micropyle. 13. The embryonic root is called the radicle. 14. The embryonic shoot is called the plumule. 15. Dicot seeds have two cotyledons; monocot seeds have one cotyledon.

III. True or False (with corrections for false statements)

Q1. In cymose inflorescence, the main axis grows indefinitely.

AnswerFalse — Correction: In cymose inflorescence, the main axis TERMINATES in a flower and does NOT grow indefinitely. It is in racemose inflorescence that the main axis grows indefinitely.

Q2. Apple is a true fruit.

AnswerFalse — Correction: Apple is a FALSE fruit (pseudocarp). The fleshy, edible part develops from the thalamus, not the ovary. The core (containing seeds) develops from the ovary.

Q3. Dicot seeds have two cotyledons.

AnswerTrue — Dicot seeds (e.g., bean, pea) have two cotyledons that store food or absorb it from the endosperm. Monocot seeds (e.g., maize, rice) have one cotyledon.

Q4. In marginal placentation, ovules are attached to the central axis.

AnswerFalse — Correction: In marginal placentation, ovules are attached along the ventral suture (margin) of the ovary (e.g., pea, bean). Axile placentation has ovules on the central axis.

Q5. A staminate flower has only pistils.

AnswerFalse — Correction: A staminate flower has only STAMENS (male parts). A pistillate flower has only pistils (female parts).

IV. Match the Following

Column A	Column B	Answer
1. Racemose	(a) Main axis terminates in a flower	(b) Main axis grows indefinitely
2. Cymose	(b) Main axis grows indefinitely	(a) Main axis terminates in a flower
3. True fruit	(c) Develops from thalamus	(d) Develops from ovary
4. False fruit	(d) Develops from ovary	(c) Develops from thalamus
5. Dicot seed	(e) One cotyledon	(f) Two cotyledons
6. Monocot seed	(f) Two cotyledons	(e) One cotyledon

V. Answer Briefly (2-mark questions)

Q1. What is inflorescence? Name its two main types.

Answer

Inflorescence is the arrangement of flowers on the floral axis (peduncle). The two main types are: 1. Racemose: Main axis grows indefinitely, flowers in acropetal order (oldest at base, youngest at tip) 2. Cymose: Main axis terminates in a flower, flowers in basipetal order (oldest at tip, youngest at base)

Q2. Distinguish between true fruit and false fruit.

Answer

| Feature | True Fruit | False Fruit | |---|---|---| | Develops from | Ovary | Parts other than ovary (thalamus, calyx, etc.) | | Examples | Mango, Tomato, Pea | Apple, Strawberry, Cashew | | Edible part in apple | — | Thalamus (not ovary) |

Q3. What is placentation? Name three types.

Answer

Placentation is the arrangement of ovules inside the ovary. Three types are: 1. Marginal: Ovules along the ventral suture — e.g., Pea, Bean 2. Axile: Ovules on the central axis — e.g., Tomato, Lily 3. Parietal: Ovules on the inner wall — e.g., Mustard

Q4. Describe the structure of a dicot seed.

Answer

A dicot seed (e.g., bean) consists of: 1. Seed coat: Testa (outer) + Tegmen (inner) — protects the embryo 2. Hilum: Scar where the seed was attached to the fruit 3. Micropyle: Small pore for water absorption 4. Embryo: Two cotyledons (store food) + Plumule (future shoot) + Radicle (future root) 5. Endosperm: Present in albuminous seeds (e.g., castor); absent in exalbuminous seeds (e.g., bean)

VI. Answer in Detail (5-mark questions)

Q1. Describe the structure of a flower with examples.

Answer

A typical flower has four whorls arranged on the thalamus (receptacle): 1. Calyx (Sepals): - Outermost whorl, usually green - Protects the flower bud before opening - Sepals may be free (polysepalous) or fused (gamosepalous) - Function: Protection of the inner whorls 2. Corolla (Petals): - Second whorl, usually brightly coloured - Attracts pollinators (insects, birds) - Petals may be free (polypetalous) or fused (gamopetalous) - Function: Attraction and protection of reproductive organs 3. Androecium (Stamens): - Male reproductive whorl - Each stamen has: Filament (stalk) + Anther (pollen-producing) - Stamens may be free (polyandrous) or fused (monadelphous, diadelphous) - Function: Produce pollen grains (male gametophyte) 4. Gynoecium (Pistil/Carpel): - Female reproductive whorl - Each pistil has: Stigma (receives pollen) + Style (stalk) + Ovary (contains ovules) - Carpels may be free (apocarpous) or fused (syncarpous) - Function: Produce ovules (female gametophyte) and develop into fruit after fertilisation

Q2. Describe the different types of placentation with examples.

Answer

Placentation is the arrangement of ovules on the placenta inside the ovary. 1. Marginal: Ovules are arranged along the ventral suture (margin) of the ovary in a single row. The ovary is unilocular. - Examples: Pea, Bean, Groundnut 2. Axile: Ovules are attached to the central axis in a multilocular ovary. The septa divide the ovary into chambers. - Examples: Tomato, Lily, Hibiscus, Lemon 3. Parietal: Ovules are attached to the inner wall (parietal region) of the ovary. - Examples: Mustard, Argemone, Cleome 4. Free Central: Ovules are attached to the central axis without any septa. The ovary is unilocular. - Examples: Dianthus, Primrose, Silene 5. Basal: A single ovule is attached at the base of the ovary. - Examples: Sunflower, Marigold, Aster

Q3. Compare dicot seed and monocot seed.

Answer

| Feature | Dicot Seed | Monocot Seed | |---|---|---| | Cotyledons | Two | One (scutellum) | | Seed coat | Testa + Tegmen (separate) | Fused with pericarp | | Endosperm | May be present or absent | Always present (large, starchy) | | Embryo | Large, with two cotyledons | Small, with one cotyledon | | Plumule | Well-developed | Well-developed, enclosed in coleoptile | | Radicle | Well-developed | Enclosed in coleorhiza | | Aleurone layer | Absent | Present (protein-rich outer layer of endosperm) | | Examples | Bean, Pea, Gram | Maize, Rice, Wheat |

Common Mistakes to Avoid

Confusing racemose and cymose: Racemose = indefinite growth, acropetal order. Cymose = definite growth (terminates in flower), basipetal order.
Calling apple a true fruit: Apple is a FALSE fruit. The edible part is the thalamus, not the ovary.
Confusing staminate and pistillate: Staminate = only stamens (male). Pistillate = only pistils (female).
Confusing placentation types: Marginal = ovules on the margin (pea). Axile = ovules on central axis (tomato). Parietal = ovules on inner wall (mustard). Learn with examples.
Confusing cotyledons in dicots vs monocots: Dicots have TWO cotyledons. Monocots have ONE cotyledon (scutellum).
Forgetting that monocot seed coat is fused with fruit wall: In monocots (like maize), the seed coat is fused with the pericarp. In dicots, they are separate.

Exam Checklist

[ ] Can you name and describe all four whorls of a flower?
[ ] Can you distinguish between complete and incomplete, bisexual and unisexual flowers?
[ ] Can you explain actinomorphic and zygomorphic symmetry?
[ ] Can you describe the types of aestivation with examples?
[ ] Can you describe the types of placentation with examples?
[ ] Can you distinguish between racemose and cymose inflorescence?
[ ] Can you distinguish between true fruit and false fruit?
[ ] Can you describe the structure of a dicot seed and a monocot seed?
[ ] Can you explain placentation, aestivation, and phyllotaxy with examples?
[ ] Can you compare dicot seed and monocot seed (at least 6 points)?

Frequently Asked Questions

The four whorls of a flower are: (1) Calyx (sepals — protective), (2) Corolla (petals — attractive), (3) Androecium (stamens — male reproductive), (4) Gynoecium (pistil/carpel — female reproductive).