The extensive mercantile interests of the Herennii are attested by several authors, who describe the family's participation in the Sicilian and African trade, and especially their involvement in purchasing and exporting silphium, a medicinal herb of great value in antiquity, which grew only along a short stretch of the African coast, and defied all attempts to cultivate it. The Herennian interest in trade is attested by the surname Siculus (a Sicilian), the settlement of a merchant named Herennius at Leptis Magna, the legend of the founding of a temple to Hercules at Rome, and a coin of the gens bearing a representation of the goddess Pietas on the obverse, and on the reverse Amphinomus carrying his father, a reference to the legend of the two brothers of Catana, who escaped an eruption of Mount Aetna carrying their aged parents.