The Collaborative International Dictionary of English v.0.48:
Flower-de-luce \Flow"er-de-luce"\, n. [Corrupted fr.
A genus of perennial herbs (Iris) with swordlike leaves and
large three-petaled flowers often of very gay colors, but
probably white in the plant first chosen for the royal French
Note: There are nearly one hundred species, natives of the
north temperate zone. Some of the best known are Iris
Germanica, I. Florentina, I. Persica, I.
sambucina, and the American I. versicolor, I.