The proximal end of the filament of a stamen is attached to which part of the flower?
The filament is the long, slender stalk of the stamen. Its proximal end (the base) is attached to the Thalamus (receptacle) or sometimes to the Petal (epipetalous condition). The distal end bears the Anther.
Ref: Diagram of a flower highlighting the attachment point of the stamen filament.