Notations of purple tinged foliage bases, spathes, rhizomes, etc. seem to never , or very rarely mentioned in the AIS descriptions, or by the introducer. Some vendor's catalogs have mentioned it, there were some period "iris handbooks' that seemed to list it as one of the "descriptors," also, but mostly one has to rely on "aftermarket" lists of pbf, (HIPS, Cubits, Irises of Shadow wood, etc.) What I find interesting about the trait is it's "variability", some cult. display early season, and fade to nothing , after bloom, some "show' all season, and some don't show any color till weather cools in the fall. Rainfall amounts seem to make a difference, too....Arlyn