A friend saw it one day and told me her elderly mother had a plant in her garden that gets rid of warts.
My dad put a shard of some silvery white crystallized substance into a wart
Salicylic acid is a well established wart treatment. It's found in plants, so the use of a plant containing it might also work, and the white crystallised substance was probably this too.
https://www.medicalnewstoday.com/articles/324732#how-to-use