Reproduction in Plants - NEET 2026

Plant Reproduction

Focus on double fertilisation and embryo sac structure — these appear every year.

Flower Structure & Pollination

Stamen (male): Filament + anther. Each anther has 4 microsporangia (pollen sacs) → pollen grains (male gametophytes).

Pistil (female): Stigma + style + ovary. Ovule inside ovary → female gametophyte (embryo sac).

Pollination types: Autogamy (same flower), Geitonogamy (same plant, different flower — functionally cross-pollination genetically), Xenogamy (different plant — true cross-pollination).

Agents: Wind (anemophily) — light, dry pollen, no nectaries. Water (hydrophily) — Vallisneria. Insect (entomophily) — colourful, fragrant, nectar, sticky pollen.

Double Fertilisation

Embryo sac (female gametophyte): 8-nucleate, 7-celled structure: Egg cell (1) + Synergids (2) + Central cell with 2 polar nuclei (1) + Antipodal cells (3).

Pollen tube: Carries 2 male gametes. One gamete fuses with egg cell → zygote (2n) → embryo. Second gamete fuses with 2 polar nuclei → primary endosperm nucleus (3n) → endosperm (food for embryo).

Double fertilisation = syngamy + triple fusion. Unique to angiosperms. Discovered by Nawaschin (1898).

Endosperm types: Nuclear (free nuclear divisions first — coconut water stage), Cellular (wall formed after each division), Helobial.

Seed & Fruit Development

After fertilisation: Zygote → embryo. Ovule → seed. Ovary wall → pericarp (fruit wall). Ovary → fruit.

Parthenocarpy: Fruit without fertilisation → seedless fruits. Banana, seedless grape, orange induced by gibberellins.

Apomixis: Seed formation without fertilisation. Includes agamospermy (embryo from maternal tissue), vegetative propagation.

Polyembryony: Multiple embryos in one seed. Citrus (lemon, orange) — nucellus gives rise to extra embryos.

Outbreeding Devices

Dichogamy: Pollen release and stigma receptivity at different times. Protandry (pollen before stigma — sunflower, rose). Protogyny (stigma before pollen).

Herkogamy: Physical barrier between stamen and pistil (Gloriosa).

Self-incompatibility: Pollen from same plant rejected by stigma at molecular level (S-locus recognition). Promotes outbreeding.

Dioecy: Separate male and female plants (papaya, date palm) — ensures cross-pollination.

Plant Reproduction Fact Vault

Embryo Sac Structure

Total cells: 7 (8 nuclei)
Egg cell: 1
Synergids: 2
Central cell (2 polar nuclei): 1
Antipodal cells: 3
Total: 7 cells, 8 nuclei

Synergids help guide pollen tube. Antipodal cells degenerate after fertilisation.

Double Fertilisation Products

Syngamy: egg + male gamete → 2n zygote
Triple fusion: 2 polar nuclei + gamete → 3n endosperm
Endosperm ploidy: 3n
Embryo ploidy: 2n
Unique to: Angiosperms

Endosperm nourishes the developing embryo — equivalent to yolk in eggs

Special Terms

Apomixis: seed without fertilisation
Parthenocarpy: fruit without fertilisation
Polyembryony: multiple embryos/seed
Agamospermy: embryo from diploid cell
Cleistogamy: pollination in closed flower

Cleistogamy (Viola, Oxalis) ensures self-pollination — pollen never exposed to air

Pollination Agents

Wind (anemophily): dry, light pollen, no scent
Water (hydrophily): Vallisneria (submerged)
Insect (entomophily): nectar, fragrance, sticky pollen
Bird (ornithophily): red/orange flowers, no scent
Bat (chiropterophily): large, drab flowers, nocturnal

Yucca and Yucca moth — obligate mutualism example

Worked Examples

EasyHow many cells are present in a typical angiosperm embryo sac at maturity?▾

(A) 4 (B) 6 (C) 7 (D) 8

Mature embryo sac = 7 cells, 8 nuclei. Composition: 1 egg cell + 2 synergids + 1 central cell (with 2 polar nuclei) + 3 antipodal cells = 7 cells. The central cell has 2 nuclei → total 8 nuclei.

Answer: (C) 7 cells

MediumWhat is the ploidy of the primary endosperm nucleus formed after triple fusion?▾

Triple fusion: 2 polar nuclei (each 1n) + 1 male gamete (1n) = primary endosperm nucleus (3n). Endosperm is therefore triploid (3n). This nourishes the embryo during its development.

Answer: 3n (triploid)

HardSeedless fruits in banana are produced by a process called:▾

(A) Apomixis (B) Parthenocarpy (C) Polyembryony (D) Agamospermy

Parthenocarpy = fruit development WITHOUT fertilisation → no seeds. Banana, seedless grapes, some citrus. Can be induced by gibberellins or auxins (like 2,4-D). Apomixis = seeds without fertilisation (no fruit involved). Polyembryony = multiple embryos in one seed.

Answer: (B) Parthenocarpy

Mistake DNA

❌ Confusing apomixis with parthenocarpy

Apomixis = SEED formation without fertilisation. Parthenocarpy = FRUIT formation without fertilisation. Both avoid fertilisation but the product is different (seed vs fruit).

Fix: Apomixis → no fertilisation → seed. Parthenocarpy → no fertilisation → fruit (no seed inside).

❌ Counting 8 cells in embryo sac

Embryo sac has 7 CELLS but 8 NUCLEI. The central cell has 2 polar nuclei. Students confuse cell count with nuclei count.

Fix: 7 cells, 8 nuclei. Central cell = 1 cell with 2 nuclei.

❌ Saying endosperm is diploid

Endosperm is TRIPLOID (3n) — formed by fusion of 2 polar nuclei (2n total) + 1 male gamete (1n). It is unique to angiosperms and one of the most nutrition-rich tissues in nature (wheat endosperm = flour).

Fix: Endosperm = 3n. Embryo = 2n. Triple fusion = 3 nuclei fuse.

Chapter Intelligence

PYQ Frequency

Double fertilisation: 1–2 Q/year
Embryo sac structure: 1 Q/year
Apomixis/parthenocarpy: 1 Q/year

2026 Prediction

High: Endosperm ploidy
Expected: Outbreeding devices (dichogamy types)
Watch: Polyembryony examples

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