[1]Shrubs, which are generally one part juice or fruit macerated with sugar and boiled with vinegar, were mixed with water in 18th century America for refreshment.
As a mixture of fruit and alcohol, the shrub is related to the punch, however punches were normally served immediately after mixing the ingredients, whereas shrubs tended to have a higher concentration of flavour and sugar and could be stored for later use, much like a pre-made mixer.
But things are changing in the ever-bubbling world of cocktails. Tart, acidic and weirdly, wonderfully refreshing, drinking vinegars known as “shrubs” have seen a return since 2011 and a rise in 2012. Sometimes they’re added to soda water as an alternative to sodas, and sometimes they’re mixed with the cocktail as a mouth-pleasing alternative to predictable acids such as lemons and limes. The acidity of the shrub makes it well suited as an aperitif or in place of bitters in cocktails. Unlike cocktails acidulated with citrus, vinegar-based drinks remain clear when shaken.
Links:
[1] http://archive.asianage.com/shrub11jpg-426