The Herball: or, Generall history of plantes (1597) pp. 49-50
John Gerard

5. This kinde of Flower de-luce came first from Portingale [Portugal] to us. It bringeth foorth in the spring time flowers of a purple or violet colour, smelling like a violet, with a white hairie welt downe the middle. The roote is thick and short, stubborne or harde to breake. In leaves and shew it is like to the lesser Flower de-luce of Dalmatia, but the leaves be more spred abroad, and it commonly hath but one flower upon one stalke, which in Autumne flowreth again, and bringeth foorth the like flowers, for which cause it was called Iris biflora.

Reblooming Iris Bibliography