Ochrea, (Latin ochrea, greave or protective legging), also spelled ocrea, is a plant structure formed of stipules fused into a sheath surrounding the stem, and is typically found in the Polygonaceae. In palms it denotes an extension of the leaf sheath beyond the petiole insertion. ... Found on http://en.wikipedia.org/wiki/Ochrea
O'chre·a noun ; plural Ochreæe . [ Latin ] 1. (Antiq.) A greave or legging. 2. (Botany) A kind of sheath formed by two stipules united round a stem. Found on http://www.encyclo.co.uk/webster/O/9