Posted by scvirginia (Charleston, SC - Zone 9a) on Jun 25, 2020 7:48 PM concerning plant:
Description from the 1933 catalog, Royal Iris Gardens (J. C. Nicholls, Jr., Camillus, NY), p.72:
IODANTHA. 4 ft. One of the largest and tallest of the dark Species; very large shapely blooms of deep rich blackish blue. A glorious mass of deep color; very strong grower.