Ocreas

Part of speech: noun

Definitions

1. A botanical term referring to a sheath formed by fused stipules that encircles the stem above the node in certain plants
2. A plant structure created when stipules grow together into a tubular covering around the stem at a joint
3. The protective collarlike sheath found at a leaf node in some species, resulting from the union of stipular parts

Etymology: Ocreas is the plural of "ocrea," the collar-like sheath that wraps a plant stem at a node. The plural is the form botanists use, following the Latin "ocreae," the plural of the Latin "ocrea." The singular comes from a Latin word for a greave, the piece of armor that protected the lower leg. Botanists applied it to the sheath because a stem wrapped in a tubular collar looked like a leg encased in metal. The plant sense is a figurative extension of the older armor sense.