Diadelphous stamens refer to stamens united into how many groups?

• A. All fused into one
• B. Stamens reduced
• C. Two groups
• D. Stamens free

Answer: (C)

Stamens can be arranged in different ways by filaments fusing together. The term diadelphous describes a pattern where the stamens are organized into two separate bundles or groups by fusion of their filaments. This two-group arrangement is characteristic in many legumes, where typically most of the stamens form one fused cluster and a portion forms a second, distinct cluster. The name itself comes from Greek roots meaning two and brother/paired, signaling these two united groups.

So why is two groups the right idea? Because diadelphous specifically denotes that the androecium is split into two united sets, not one single fused mass, not all stamens remaining completely free, and not a general reduction in stamen number. If the stamens were all fused into a single group, that would be monadelphous. If each stamen remained entirely separate, the stamens would be free. If there were several separate groups beyond two, that would be polyadelphous.