According to the History Channel, the heart symbol as we know it may have originated from the silphium plant, a species of giant fennel that once grew on the North African coastline near the Greek colony of Cyrene. The ancient Greeks and Romans used silphium as both a food flavoring and a medicine—it supposedly worked wonders as a cough syrup—but it was most famous as an early form of birth control. Ancient writers and poets hailed the plant for its contraceptive powers, and it became so popular that it was cultivated into extinction by the first century A.D. (legend has it that the Roman Emperor Nero was presented with the last surviving stalk). Silphium’s seedpod bore a striking resemblance to the modern Valentine’s heart, leading many to speculate that the herb’s associations with love and sex may have been what first helped popularize the symbol. The ancient city of Cyrene, which grew rich from the silphium trade, even put the heart shape on its money.