from The Century Dictionary and Cyclopedia
- n. The common blue flag, Iris versicolor, which grows in wet places or even in water.
- n. The yellow flag, Iris Pseudacorus. Also called yellow iris and flower-de-luce.
Sorry, no etymologies found.
I have already stated to you that if any definite flower is meant by these triple groups of leaves, which take their authoritatively typical form in the crowns of the Cretan and Laciuian Hera, it is not the violet, but the purple iris; or sometimes, as in Pindar's description of the birth of Ismus, the yellow water-flag, which you know so well in spring, by the banks of your Oxford streams.
The palm, in the shorthand of their art, gradually becomes a symmetrical branched ornament with two pendent bosses; this is again confused with the Greek iris, (Homer's blue iris, and Pindar's water-flag,) -- and the Florentines, in adopting Byzantine ornament, read it into their own Fleur-de-lys; but insert two poppyheads on each side of the entire foil, in their finest heraldry.
Because Dr. Priestley observed the pure air to come from both sides of the leaves and even from the stalks of a water-flag, whereas one side of the leaf only serves the office of lungs, and certainly not the stalks.