- (in Orchidaceae) the central petal, which is often lobed or spurred, and hence differs from the other two petals;
- (in Zingiberaceae) a large petaloid, sometimes lobed, object which together with the stamen forms the androecium.
Copyright: Mark Hyde, Bart Wursten, Petra Ballings and Meg Coates Palgrave, 2002-17
Hyde, M.A., Wursten, B.T., Ballings, P. & Coates Palgrave, M.
. Flora of Zimbabwe: Glossary details: labellum.
http://www.zimbabweflora.co.zw/speciesdata/glossary-display.php?glossary_id=393, retrieved 30 March 2017