What part of the licorice plant gives the candy its distinctive flavor?

Liquorice (British English) or licorice (American English) is the root of Glycyrrhiza glabra from which a sweet flavor can be extracted.

The scent of licorice root comes from a complex and variable combination of compounds, of which anethole is up to 3% of total volatiles. Much of the sweetness in licorice comes from glycyrrhizin, which has a sweet taste, 30–50 times the sweetness of sugar. The sweetness is very different from sugar, being less instant, tart, and lasting longer.

Licorice, which grows best in well-drained soils in deep valleys with full sun, is harvested in the autumn two to three years after planting. Countries producing licorice include India, Iran, Italy, Afghanistan, the People’s Republic of China, Pakistan, Iraq, Azerbaijan, Uzbekistan, Turkmenistan, Turkey, and the United Kingdom.

Licorice flavor is found in a wide variety of candies or sweets. In most of these candies, the taste is reinforced by aniseed oil so the actual content of licorice is very low. Most licorice is used as a flavoring agent for tobacco. For example, M&F Worldwide reported in 2011 that about 63% of its licorice product sales are to the worldwide tobacco industry for use as tobacco flavor enhancing and moistening agents in the manufacture of American blend cigarettes, moist snuff, chewing tobacco, and pipe tobacco.