a European iris, Iris pseudacorus, naturalized throughout eastern North America, with blue-green leaves and violet-veined, yellow flowers and growing in moist places.
Origin of water flag
First recorded in 1570–80
Also called yellow flag.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for water flag
Dark bulrushes edged the shores, and the water-flag planted its golden tents between.The Song of Songs|Hermann Sudermann