It's worn in the buttonhole of a lapel, so the name of this floral accessory is French for "buttonhole"
[DOC] [TLE] Black Tie Guide | Classic Accessories [PAR] Truly classic cufflinks are connected with a chain or links (thus the name) ... 
Classic accessories add the finishing touches to a man's black-tie kit and ... (
buttonhole in UK) can be correctly worn in the buttonhole on