Which herb is a key ingredient in traditional pesto?

Which herb is a key ingredient in traditional pesto? Basil is the key herb in the classic sauce, especially the Genovese style associated with Genoa and Liguria, Italy.

Traditional pesto alla genovese combines basil with extra-virgin olive oil, garlic, pine nuts, and hard cheeses such as Parmigiano-Reggiano and pecorino. The name comes from the Genoese verb pestâ, meaning “to pound,” describing preparation with a mortar and pestle.

Basil was not always part of the sauce’s earliest ancestors. Ancient Roman moretum was a crushed mixture of herbs, garlic, cheese, oil, and sometimes nuts, while medieval Ligurian agliata was based mainly on garlic and walnuts. Basil became central to modern pesto recipes documented in the 1850s and 1860s.

Parsley, mint, and oregano can appear in modern pesto variations, but substituting them changes the style. Authentic Genovese pesto specifically favors local Genovese basil, a cultivar of Ocimum basilicum.