Water lily, Yellow pond lily
The roots of the water lily plant are dried and used to relieve a dry throat or the onset of a cold. Ruth Welsh said,
"...you only take small little tiny pieces."
The roots are also used to ease a sore back. Ruth describes how to make this,
…cut a piece off [the main root]…a foot or a foot and a half long…heat the root….split the root and put it on each of [the] back and tie [it in place].
Source: Andre, Alestine, Nan t'aih nakwits'inahtsìh (The Land Gives Us Strength) (2006)