AbstractThe presence of p-coumarate (pCA) in plant cell walls is generally considered to be a trait present only in commelinid monocots. Here, we show that this long-held overgeneralizing assumption is incorrect and that mulberry trees (Morus) are eudicot plants that have lignins derived in part from monolignol pCA esters. As in commelinid monocots, the lignin-bound pCA acylates the sidechain γ-hydroxyl of both coniferyl and syringyl units. This discovery expands mulberry’s potential applications to include being a source of p-coumaric acid, a supplier of nutritious berries, a forage crop, a decorative plant, and the main food source for silkworms.