A single-seeded, dry, non-dehiscent fruit in which pericarp is united with the seed is known as

A caryopsis is a dry, one-seeded fruit where the fruit wall (pericarp) is completely fused to the seed coat, making them indistinguishable - typical of grasses like wheat and corn. An achene has a separate pericarp and seed, a cypsela is similar to achene but develops from an inferior ovary, and a loment is a segmented legume fruit.