any of several plants belonging to the genus Justicia, of the acanthus family, growing in water or wet places, especially J. americana, of North America, having clusters of pale violet to white flowers.
Origin of water willow
First recorded in 1575–85
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for water willow
In a general way, I have a mind as round as a ball, and a character fresh as a water-willow.Diderot and the Encyclopdists|John Morley