In 1893 the US Supreme Court decided Nix v. Hedden, which asked whether the tomato is a fruit or a vegetable for tariff purposes. This episode traces how the tomato reached that point. Its wild ancestor, Solanum pimpinellifolium, grew in western South America and produced pea-sized berries. Mesoamerican farmers domesticated it, and the Aztecs grew many varieties. After Spanish conquest it spread through Europe, but John Gerard’s 1597 book called it poisonous, and many in Britain kept it as an ornamental plant.

We explain the nightshade chemistry behind that fear, including tomatine and solanine in the leaves and green fruit, and the shift to lycopene and sugar as the fruit ripens. We cover buzz pollination by bumblebees, the uniform ripening mutation that cut sugar content and helps explain bland supermarket tomatoes, the failure of the Flavr Savr, and why umami made tomatoes central to cuisines worldwide. We finish with the court’s reasoning and practical storage advice.

• How a pea-sized Andean berry was domesticated in Mesoamerica
• Why Northern Europeans once feared the tomato as poisonous
• Alkaloids, lycopene and the ripening strategy of the tomato plant
• Linkage drag, the uniform ripening mutation and the Flavr Savr
• The Nix v. Hedden ruling and why you shouldn’t refrigerate tomatoes