In many of Taiwan's cafes, a drink made from a purple-leafed plant is often served with some fresh lemon juice. When you put the lemon juice into the purple-to-brownish liquid, it turns into a bright pink. Does anyone know the English or binary name of that plant? We grow the plant here in the yard in US (it grows well in central New Jersey), just don't know the name. In Mandarine it's "Tse-(purple)Shu". Thanks.