Yes, I'd heard of
cascara, as a laxative given to children in the 1950s. (I was a child in the 1950s.)
It seems the word has had a new lease of life. I quote from the Australian website Broadsheet this month:
New additions include an iced cascara tea, which marries cascara (the dried skin of coffee cherries) with native aniseed myrtle.
This is apparently quite unrelated to the plant in the buckthorn family that yields the laxative. At least I hope so.
In any case, I agree the word is rare these days.