Question
Describe the four whorls of a flower — calyx, corolla, androecium, and gynoecium. What is the function of each whorl? What makes a flower “complete”?
Solution — Step by Step
A typical flower has four whorls arranged on the thalamus (receptacle):
| Whorl | Parts | Function |
|---|---|---|
| Calyx (outermost) | Sepals (usually green) | Protect the bud before it opens |
| Corolla | Petals (colourful) | Attract pollinators |
| Androecium | Stamens (anther + filament) | Male reproductive whorl — produces pollen |
| Gynoecium (innermost) | Carpels (stigma + style + ovary) | Female reproductive whorl — contains ovules |
Each stamen has a filament (stalk) and an anther (produces pollen grains). Pollen grains contain male gametes. A flower may have many stamens (e.g., rose) or just a few (e.g., mustard has 6).
The carpel (or pistil) has three parts: stigma (receives pollen — sticky surface), style (tube connecting stigma to ovary), and ovary (contains ovules, which develop into seeds after fertilisation). A flower may have one carpel (monocarpellary) or many (multicarpellary — free or fused).
flowchart TD
A[Flower Structure - 4 Whorls] --> B[Calyx: Sepals - protection]
A --> C[Corolla: Petals - attract pollinators]
A --> D[Androecium: Stamens - male]
A --> E[Gynoecium: Carpels - female]
D --> D1[Anther produces pollen]
D --> D2[Filament supports anther]
E --> E1[Stigma receives pollen]
E --> E2[Style connects to ovary]
E --> E3[Ovary contains ovules]Why This Works
A complete flower has all four whorls. An incomplete flower is missing one or more whorls. A bisexual (perfect) flower has both androecium and gynoecium. A unisexual flower has only one (either male or female). Examples: hibiscus is bisexual and complete; papaya flowers are unisexual.
Common Mistake
Students confuse complete with bisexual. A complete flower has all 4 whorls (including petals and sepals). A bisexual flower has both male and female parts — but may lack petals or sepals (making it bisexual but incomplete). Most flowers are both, but the terms are different.
For NEET: the calyx and corolla together are called the perianth. When sepals and petals look alike (as in lily), they are called tepals. This terminology appears in morphology questions.