Antheridium and Archegonium: Male and Female Sex Organs of Lower Plants
Biology · Plant Kingdom · NEET
The antheridium is the MALE sex organ. It makes many motile sperms called antherozoids (biflagellate). The archegonium is the FEMALE sex organ. It is flask-shaped and makes just one egg. Both are multicellular and are found in bryophytes and pteridophytes. Memory hook: "Antheridium = A for A-lot of sperms; Archegonium = flAsk with one egg."
Antheridium (male) makes many swimming antherozoids; the flask-shaped archegonium (female) holds one egg. Water carries the sperm from antheridium to archegonium. Both organs sit on the haploid (n) gametophyte.
Your doubts, answered
Which one is male and which one is female?
Antheridium is the MALE sex organ. Archegonium is the FEMALE sex organ. Easy trick: Antheridium and Antherozoid both start with 'Anther', and antherozoids are the male gametes (sperms). So Antheridium = male. Archegonium is the other one, so it is female.
What does each one produce?
The antheridium produces many biflagellate antherozoids (motile male gametes / sperms). The archegonium is flask-shaped and produces only ONE egg (female gamete). NEET loves this contrast: many sperms vs a single egg.
Why is the archegonium called flask-shaped?
Because it looks like a flask or a bottle. It has a swollen lower part called the venter (holds the single egg) and a long neck on top. The antherozoid swims down the neck to reach the egg. Antheridium is usually more rounded or club-shaped, not flask-shaped.
Are antheridium and archegonium haploid (n) or diploid (2n)?
They are HAPLOID (n). They are borne on the gametophyte, and the whole gametophyte body is haploid. Since gametes must be haploid, the sex organs that make them are haploid too. This is a common NEET trap: students wrongly mark them as 2n.
Why do these plants need water for fertilisation?
The antherozoids are motile and have flagella, so they must SWIM. Water is required to carry the antherozoids from the antheridium to the mouth of the archegonium. Without a film of water, the sperms cannot reach the egg. This is why bryophytes are called 'amphibians of the plant kingdom'.
Which plant groups have antheridia and archegonia?
Bryophytes (liverworts and mosses) and pteridophytes (ferns etc.) both bear antheridia and archegonia. Gymnosperms also have archegonia, but their gametophytes are not free-living. Note: antheridium and archegonium are sex organs, NOT flowers — lower plants have no flowers.
Are these sex organs single-celled or many-celled?
They are MULTICELLULAR (made of many cells). This is a key difference from algae, where sex organs are usually single-celled (unicellular). In bryophytes and pteridophytes the sex organs became multicellular, with a protective jacket of sterile cells.
⚠️ The NEET trap ✗ Antheridium and archegonium are diploid (2n) structures that need wind for pollination. ✓ Both are HAPLOID (n) because they sit on the haploid gametophyte, and the male gametes (antherozoids) need WATER, not wind, to swim to the archegonium. 🧠 Lower plants = no flowers, no wind pollination. Antherozoids SWIM, so water is the delivery agent — remember NEET 2016: 'transport of male gametes in bryophytes and pteridophytes requires water'.
Real NEET questions
2016
In bryophytes and pteridophytes, transport of male gametes requires:
A · Wind
B · Insects
C · Birds
D · Water ✓
Solution: Both bryophytes and pteridophytes have flagellated, motile male gametes (antherozoids) that are released from the antheridium. These antherozoids must SWIM through a film of external water to reach the archegonium and fuse with the egg. Wind, insects and birds are pollination agents for seed plants only. So the answer is Water. This is exactly why these groups depend on moist habitats for sexual reproduction.
2025
Stages in the life cycle of pteridophytes — arrange in the correct sequence: A. Prothallus stage; B. Meiosis in spore mother cells; C. Fertilisation; D. Formation of archegonia and antheridia in gametophyte; E. Transfer of antherozoids to the archegonia in presence of water.
A · D, E, C, A, B
B · E, D, C, B, A
C · B, A, D, E, C ✓
D · B, A, E, C, D
Solution: The sporophyte's spore mother cells undergo meiosis to make spores (B). A spore grows into the prothallus / gametophyte (A). The prothallus then forms the sex organs archegonia and antheridia (D). Antherozoids are transferred to the archegonium through water (E). Fusion of gametes gives the zygote — fertilisation (C). Correct order: B, A, D, E, C. Notice antheridia/archegonia form BEFORE the water-aided transfer and fertilisation.
Solved Plant Kingdom NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Antheridium is the MALE sex organ. It produces motile biflagellate antherozoids (sperms). The female organ is the archegonium.
How many eggs does one archegonium produce?
Only ONE egg. The archegonium is flask-shaped and its swollen base (venter) holds a single egg. In contrast, one antheridium makes many antherozoids.
Are antheridium and archegonium haploid or diploid?
Both are haploid (n). They develop on the haploid gametophyte, so all their cells and the gametes they make are haploid.
Which plants have both antheridia and archegonia?
Bryophytes (liverworts, mosses) and pteridophytes (ferns) bear both antheridia and archegonia on their gametophytes.
Why is water needed for fertilisation in these plants?
Because the male gametes (antherozoids) are flagellated and swim. Water carries them from the antheridium to the archegonium. No water means no fertilisation.
