Japanese iris; blue flag; Iris ensata
something that comes too late to be useful; (lit.) iris (blooming) on the 6th (i.e. one day too late for the Boy's Day celebration)
(of a choice) one being as excellent as the other; both so beautiful it is hard to choose between
Arctic iris (Iris setosa)
gladiolus; Dutch iris (Iris x hollandica)
German iris (Iris germanica)