Sentence:  The form of the flower is highly dependent on the structure of the <WSD>receptacle</WSD>, even though this may not always be obvious externally. The <WSD>receptacle</WSD> is also called the "floral axis", or it is sometimes called the "torus", which may be translated as "swelling". These expressions "per se" imply that, although in the majority of cases the <WSD>receptacle</WSD> is greatly reduced, it is frequently thickened in a capitate form or broadened into a definitely disc-like shape. 
Meaning of the word marked with <WSD> tags:  The part of the flower stalk (peduncle or pedicel) to which the floral parts are attached; a thalamus, a torus.