Someone mistook my illos shown here a couple of days ago as watercolors so I thought I'd talk about my method - here's another spread from GUESS WHO'S IN THE DESERT (by Charline Profiri, Spring 2013). Textures are, of course, much easier to see actual size.
Textures are created by scanning cardboard (cactus), a crackle surface I created with gesso (roadrunner path), rocks and stones, a shadow created on the patio umbrella (background foliage on left) various papers that I've painted and scanned and further manipulated (plant leaves, mountains, sky, earth...)
I supposed it is best described as digital collage - Illustrations are created by manipulating scans of found objects, textures and hand-painted papers in Adobe Photoshop to create new patterns, adding digital paintings, and collaging it all together.