In 2007 Clarence Mahan published a wonderful book titled Classic Irises and the Men and Women Who Created Them which contained a chapter about the Iris that lost its name - 'Sans Souci'. According to Mr. Mahan's thorough research what is commonly growing all over the US as 'Honorabile' is not; its really 'Sans Souci'. Click on the photos to embiggen.
The mixing of names for these two started very early on and were known to be confused when the 1929 Checklist was published. Given the similarity it is easy to see why this error came about. The real 'Honorabile' should have a solid red fall, not a thin layer washed across the yellow, as 'Sans Souci' displays. I've been unable to locate the real 'Honorabile', tho I have collected several of its sports. A sport is a vegetative mutation that is quite rare in irises, but Sans Souci and its brethren are well known for this trait, occasionally growing a new rhizome identical in all ways but color pattern. Here's a few that have been named and introduced over the years:
In 2008 a stalk on my clump of 'Joseph's Coat Katkamier' put out flowers in a most interesting pattern - each terminal bloom was perfectly split in half between the typical 'JCK' pattern and the 'Sans Souci' pattern, with buds on the right side branches being perfect 'SS' and buds on the left branches being perfect 'JCK' blooms.
Surprisingly it did this again on a stalk in 2009. I plan to separate it out this summer and see if it remains stable. I've also heard mention from other collectors of a sport that lost all its yellow pigment and is a perfect amoena, and another that lost all its pigments and was solid ivory.
This is a fun family of iris varieties, and being Miniature Tall Beardeds they don't take up much room in the garden. I highly recommend them as excellent garden plants and they are well known for their hardiness and vigor. The AIS Bulletin published Clarance Mahan's synopsis of his book's chapter on Honorabile and Sans Souci in the 2006 issue #341, which is reprinted here , and there's excellent information on the known sports in an article from ROOTS by noted expert Jean Witt which is also at HIPS' website