Assertion A: A flower is defined as modified shoot wherein the shoot apical meristem changes to floral meristem. Reason R: Internode of the shoot gets condensed to produce floral appendages.

Both A and R are true and R is the correct explanation of A.

Both A and R are true but R is NOT the correct explanation of A.

Floral Whorls

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NCERT Class 11 · Morphology of Flowering Plants · 2 NEET questions

A flower is not just a decoration; it is a highly modified shoot system. If you cannot identify the four whorls on the thalamus, you are failing to see the structural blueprint of Angiosperms. Stop guessing and start observing the sequence.

The idea

A typical flower consists of four whorls arranged sequentially on the thalamus. These are the calyx, corolla, androecium, and gynoecium. The calyx and corolla are accessory organs, while the androecium and gynoecium are reproductive organs. Their precise spatial arrangement is fundamental to floral morphology.

Why it matters

These whorls are specialized for protection, attraction of pollinators, and sexual reproduction to ensure the survival of the species.

NEET lens

NEET focuses on the sequence of whorls from outermost to innermost. Remember: Calyx (outer) to Gynoecium (inner). Do not confuse accessory organs with reproductive organs; questions often trap you on their specific functions.

Clinical significance

In ecosystems, the failure of these floral whorls to develop or differentiate leads to reproductive sterility. Without functional androecium and gynoecium, pollination fails, collapsing the food chain. This is the biological equivalent of organ failure in human physiology.

Introduction

A complete flower has four whorls on the thalamus (receptacle): calyx (sepals), corolla (petals), androecium (stamens), gynoecium (carpels) — from outermost to innermost.

Core concept

Calyx: outermost, usually green, photosynthetic, protects bud. Can be gamosepalous (fused) or polysepalous (free). Corolla: petals, often colored for pollinator attraction. Gamopetalous or polypetalous. Perianth: when calyx and corolla are undifferentiated (tepals) — lily. Androecium and Gynoecium: reproductive whorls.

Go deeper

Perigone/perianth is common in monocots. When the flower is epigynous, the floral whorls appear to arise from the top of the ovary (inferior ovary). Hypogynous flowers have all whorls below a superior ovary.

From Class 10

You know flowers have four main parts. Each part forms a whorl. These whorls have a specific arrangement from outside to inside.