also: そうぶ
Acorus calamus, a wetland plant with aromatic rhizomes. Often associated with the Boy's Festival (端午の節句) where its leaves are used in baths.
There is a custom of taking a bath with sweet flag leaves on the Boy's Festival.
Colloquial use for Iris ensata var. ensata, a popular garden plant with large, showy flowers. The more precise term is 花菖蒲 (はなしょうぶ).
See also: 花菖蒲
Beautiful Japanese irises are blooming in the garden.