I did this painting from my Mom's purple Iris. It is done in oils and on a canvas. It is available here for you
The Purple Iris measures 16"x8" and is perfect for you. I put greens,purples,yellows,and the siennas in the painting. The background is done with darker values of purples and blues.
Title Purple Iris
Medium oils on canvas
Signed by Barbara Havilandhttp://barbarahaviland.fineartstudioonline.com/works/502079/purple-iris