Perisperm

Part of speech: noun

Definitions

1. A layer of nutritive tissue in seeds that surrounds the embryo and provides nourishment during germination
2. The stored food tissue in certain seeds that encases the developing embryo and supports its early growth
3. Nutritive material in seeds that lies outside the embryo and supplies energy for the germinating seedling

Etymology: "Perisperm" is a botanical term for the nutritive tissue surrounding the embryo in some seeds, and its parts are plain Greek. The prefix "peri-" means "around," as in "perimeter" or "perihelion," and "sperm" comes from the Greek "sperma," meaning "seed." Put together, the word describes tissue that lies around the seed, which is exactly what it names. The term was borrowed into English from French "périsperme," which was itself built from the same Greek elements. Like many botanical words, it reflects the scientific habit of the 18th and 19th centuries of assembling classical pieces into precise labels for newly studied plant structures, rather than being a word that circulated in everyday speech for centuries. The word's meaning has stayed remarkably stable. Its literal sense, "around the seed," still fits the tissue it describes, so there is no surprising semantic shift to report. Its interest lies mainly in how neatly the Greek pieces map onto the biology.