Thanks for the ID on the “mystery” plant. It is, in fact Nicotiana Sylvestris. Its intoxicating fragrance is most full in the evening when it woes the sphinx moth and the hawk moth for pollination. It is a native of Argentina and its cousin Nicitiana Tobacum was brought to France in the 16th century by Jean Nicot. Monsieur Nicot, who lived from 1530-1600, did not have to travel all the way to the Americas for it. He discovered it while serving as the French ambassador to Portugal in the garden of the Portuguese scholar and botanist Damiao de Goes. He took some cuttings and planted them in the garden of the French embassy in Lisbon and experimented with the medicinal properties of the leaves. All this experimentation led him to believe that this was a plant with extraordinary powers so he decided to name the plant after himself. When, in 1560, he sent some snuff to the French Queen, Catherine de Medici, to relieve her migraine headaches, she declared it Herba Regina, the queen’s herb. Soon the snuff and smoking fashion was the rage in the French Court.
So it is not surprising that these fragrant plants are planted in Catherine de Medici’s garden here outside the Palais Luxembourg.