A Super Bitter Herbal Plant : Serpentina Plant

As i saw this herbal plant in the roofdeck, it's familiar to me but i can't recall its name in my native tongue. A days past my neighbor picked some leaves, so i asked what she do that leaves. She said " I will make a tea and drink it. " She simply put the cleaned leaves in cup and put hot water and drink it when its not too hot . She told me that drinking it helps her kidney stone gone and its good to the body. I looked again on that plant, it has tiny flower - a tiny white flower! Finally i remember its name " white flower" in our place and its known as "serpentina". When i was young my mother gives us that hot white flower water when we suffer stomach ache or diarhea. Drinking it is hard to take because of super natural bitterness. Sometimes i vomit, so i eat sugar after i drank to fade the bitterness taste.
As i know some goods of serpentina herbal plants i searched more about it. And i found out it's benefits of serpentina herbal plant, and it has a risk too. If you like to drink it you must have knowledge about this herbal plant first. And of course it's better to see your doctor if you unwell.