The iris is one of the rare flowers whose Victorian meaning seems to explain itself. Kate Greenaway's illustrated Language of Flowers (1884) gives it as "Message". So does Henrietta Dumont's Language of Flowers, published in Philadelphia in 1851. In a set of books that disagreed about most things, two writers on opposite sides of the Atlantic agreed on this one.

The reason seems obvious once you know the name. In Greek, iris means "rainbow", and Iris was the goddess of the rainbow and the messenger of the Olympian gods, especially of Hera. A flower called after the gods' messenger meaning "message" is a neat fit. But neither book says that is why, and the Chicago History Museum notes that many floral meanings were assigned fairly arbitrarily, so the link is a likely reading rather than a recorded one.

Greenaway does not leave it there. Her list gives the German iris a different meaning entirely: "Flame". As with roses and tulips, the exact kind of flower changes what it says.

The iris also has a long life outside the flower books. Its name passed to the coloured ring of the eye in the fifteenth century. And it may be behind one of the most famous emblems in Europe: the fleur-de-lis, the "lily flower" of the French kings, which many writers have argued is really a stylised iris. That argument has never been settled, which is in keeping with everything else about the language of flowers.