"the rich distillation from the juniper-berry"
Juniper berriers ripe and new
Creative Commons Attribution Share AlikeJuniper berriers ripe and new - Credit: John Tustin

A juniper berry is not really a berry, but a seed cone, with fleshy and merged scales, which gives it a berry-like appearance. The cones are used as a spice, and give gin its distinguishing flavour. 

Juniper has been a popular flavourant for distilled spirits since the 11th century, by virtue of its perfume, flavour, and purported medicinal properties.

Gin Lane
Public DomainGin Lane - Credit: William Hogarth

A Dutch physician is credited with inventing gin. The name gin derives from the French or Dutch word for juniper (genièvre or jenever).  By the mid-17th century, numerous small Dutch and Flemish distillers had popularized the re-distillation of malt spirit or wine with juniper, anise, caraway, coriander and other spices, which were sold in pharmacies to treat various medical problems.  Gin became popular in England after the Government allowed unlicensed gin production and at the same time imposed a heavy duty on all imported spirits. Thousands of gin-shops sprang up across the country.