Biology · Sexual Reproduction in Flowering Plants · NEET
Yes. Autogamy means pollen from a flower lands on the stigma of the same flower. Because a cleistogamous flower never opens, no cross-pollen from outside can ever reach its stigma. The anthers dehisce inside the closed bud and the pollen touches the stigma right there. So there is only one possible pollen source — the flower itself. That is why NCERT says cleistogamous flowers are 'invariably autogamous'. For NEET, remember 'invariably' means 100% of the time, with no exception.
Cross-pollination needs pollen from one plant to travel to the stigma of another plant, usually carried by wind, water or an insect. A cleistogamous flower stays fully closed, so no outside agent and no outside pollen can enter. The stigma is sealed away from the world. With no route in for foreign pollen, cross-pollination is physically impossible, and only self-pollen works.
NCERT names three plants that produce both types on the same plant: Viola (common pansy), Oxalis and Commelina. The chasmogamous flowers look like normal open flowers with exposed anthers and stigma, while the cleistogamous ones stay closed. This is a common one-word or matching question in NEET, so memorise these three examples: Viola, Oxalis, Commelina.
It is both, depending on how you look at it. Advantage: cleistogamous flowers give assured seed-set even when no pollinators are present, because they do not depend on any external agent. Disadvantage: because there is no cross-pollination, there is no genetic recombination or variation from a second parent, so the offspring are less varied. NEET often frames this as a two-statement question, so hold both ideas together.
Yes. This is their main survival value. Since pollination happens inside the closed bud using the flower's own pollen, no bee, butterfly, wind or water is needed. So even in a season with few insects, or in a harsh habitat, the plant still sets seed reliably. NCERT phrases this as 'cleistogamous flowers produce assured seed-set even in the absence of pollinators'.
Given below are two statements: Statement I : Cleistogamous flowers are invariably autogamous Statement II : Cleistogamy is disadvantageous as there is no chance for cross pollination In the light of the above statements, choose the correct answer from the options given below:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Chasmogamous flowers open and expose their anthers and stigma, so they can be self- or cross-pollinated. Cleistogamous flowers never open, so pollination happens inside the closed bud and they are always self-pollinated (autogamous).
Viola (common pansy), Oxalis and Commelina produce both chasmogamous and cleistogamous flowers on the same plant. These three names are the standard NCERT examples for NEET.
They are strictly self-pollinated (autogamous). Because the flower stays closed, no foreign pollen can enter, so cross-pollination cannot occur at all.
Cleistogamous flowers give assured seed-set even when pollinators are absent, because they do not depend on any external pollinating agent.
'Invariably' means without exception. Since a cleistogamous flower can never receive outside pollen, self-pollination is the only outcome, so it is autogamous 100% of the time — a favourite NEET keyword.
