a tube-like structure sometimes split
longitudinally for part or whole of the length with the two
margins overlapping, that encloses an organ either completely or
partially, e.g. a leaf-sheath of Poaceae.
Copyright: Mark Hyde, Bart Wursten and Petra Ballings, 2002-13
Hyde, M.A., Wursten, B.T. & Ballings, P.
. Flora of Zimbabwe: Glossary details: sheath.
http://www.zimbabweflora.co.zw/speciesdata/glossary-display.php?glossary_id=674, retrieved 20 May 2013