Burrage

The OED (140) defines burrage as an obsolete form of borage, which is a genus of plants of the family Boraginacae: “Formerly much esteemed as a cordial, and is still largely used in making cool tankard, claret cup, etc.” We understand it is also good in lemonade.

Context: 
A bunch of burrage for the claret-cup
Opera: 
Act: 
Act I