perisperm

Perisperm is a nutritive tissue found in the seeds of a minority of flowering plants. It is derived from the nucellus, the maternal tissue within the ovule, rather than from the triploid endosperm formed after fertilization. In seeds with perisperm, the nucellus cells persist after fertilization and differentiate into perisperm, which fills part or all of the seed cavity and stores reserves such as starch and lipids to nourish the developing embryo.

In contrast, the more common endosperm is formed by the fusion of a sperm with two polar nuclei, creating a separate nutritive tissue that is typically not continuous with the nucellus.

Perisperm thus represents an alternative strategy of seed reserve provisioning. It can persist alongside or replace endosperm in different species. The presence and composition of perisperm can influence seed morphology and germination, and its study helps in understanding evolutionary variation in seed development.

Examples of plants reported to have perispermal tissue include species of Plantago (plantains) and Piper nigrum (black pepper), among others. In these seeds, the perisperm often appears as a relatively compact tissue rich in starch, with the embryo developing within or adjacent to it.