The tube is shorter than "Iris cristata". Similar in size to "Iris cristata". "Iris cristata" has many different cultivars. It is closely related to "Iris cristata" (another North American crested iris). In Spring, it can flower 7 to 10 days earlier than "Iris cristata". One specific species, "Iris cristata" from North America. "Iris cristata" is an accepted name by the RHS. It is similar in form to "Iris cristata" but is chromosomally different and smaller. "Iris cristata" is listed as 'endangered' in Maryland and Pennsylvania.