earthnut, (Conopodium majus), European plant of the carrot family (Apiaceae), so called because of its edible tubers. It grows in woods and fields in the British Isles and from Norway, France, Spain, and Portugal to Italy and Corsica. The slender, smooth perennial, growing 750 mm to 1 m (30 to 39 inches) high, has much-divided leaves and small, white flowers in compound umbels. The tubers, reaching 25 mm (1 inch) in diameter, are more commonly used as food on the Continent than in Britain. The peanut, or groundnut, is sometimes called earthnut.