Biology · Sexual Reproduction in Flowering Plants · NEET
A flower is a modified shoot, not a modified leaf. The whole structure grows from the shoot apical meristem, which turns into a floral meristem. The individual floral parts (sepals, petals, stamens, carpels) are modified leaves (foliar appendages), but the flower as a whole is a modified shoot. So both ideas are used: the flower = modified shoot; its parts = modified leaves.
Because the shoot apical meristem (SAM) that would normally keep making stem and leaves instead becomes a floral meristem. Three changes happen: (1) the axis stops growing in length because the internodes do not elongate, (2) the axis becomes short and condensed, and (3) the apex produces floral appendages (sepals, petals, stamens, carpels) laterally instead of ordinary leaves. A condensed shoot bearing floral parts = a flower.
The shoot apical meristem (SAM) keeps growing and keeps making leaves and internodes (indeterminate growth). When a plant decides to flower, this SAM converts into a floral meristem. The floral meristem has determinate growth: it makes a fixed set of whorls (sepals, petals, stamens, carpels) and then stops. So the key difference is: SAM keeps growing, floral meristem stops after making the flower.
The androecium (all the stamens together) is the male reproductive organ; each stamen makes pollen grains (male gametophytes). The gynoecium or pistil (carpels together) is the female reproductive organ; it contains the ovules with the embryo sac (female gametophyte). Sepals (calyx) and petals (corolla) are accessory whorls that protect and attract pollinators; they are not the reproductive organs themselves.
In a normal shoot the internodes elongate so leaves are spaced out along the stem. In a flower the floral meristem suppresses internode elongation, so all the whorls are packed very close together on a short, swollen axis called the thalamus or receptacle. This crowding is exactly why a flower looks compact and not like a leafy branch.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes. A flower is a modified shoot in which the shoot apical meristem changes into a floral meristem, the internodes do not elongate, and the condensed apex makes floral parts instead of leaves.
The flower is the seat of sexual reproduction. It carries the male organ (androecium/stamens) and the female organ (gynoecium/pistil), where pollen and ovules are formed and fertilisation happens.
From outside to inside on the thalamus: calyx (sepals), corolla (petals), androecium (stamens), and gynoecium (carpels/pistil). Calyx and corolla are accessory; androecium and gynoecium are the reproductive whorls.
The floral parts (sepals, petals, stamens, carpels) are modified leaves (foliar appendages), while the flower as a whole is a modified shoot.
It is the opening idea of Sexual Reproduction in Flowering Plants. NTA sets tricky statement questions on 'flower = modified shoot' versus 'parts = modified leaves' and on which whorl is male versus female, so getting the wording exact protects easy marks.
