Many thanks to Ouari Khemissi for this wonderful cover!
The beautiful stamp on the cover belongs to the "Ornamental Plants" series. Issued on 27th Dec 2011, it shows Night blooming Jasmine. Also known as Queen of the Night in some tropical countries, its heady fragrance can usually be smelled from as far as 300 yards away!
The other stamps in this series show Bougainvillea (15.00), Wisteria (20.00) and Mimosa (30.00).