Practice question

Diadelphous androecium is defined by filaments united into two bundles while anthers remain free. In Papilionoideae of Fabaceae, exemplified by Pisum sativum, nine stamens fuse into a sheath enclosing the ovary and one posterior stamen stays free, formula (9)+1. This arrangement protects nectar at base and guides bee foraging, keel petals must be depressed. China rose shows monadelphous tube, sunflower syngenesious where anthers unite, mustard tetradynamous 4+2 free. Diadelphous therefore reliably separates pea from other families and reflects papilionaceous floral architecture linked to legume pollination biology.