the inner whorl of sterile appendages in the flower, made up of the free or united petals which are usually membranous and coloured (not green).
Copyright: Mike Bingham, Annette Willemen, Bart Wursten, Petra Ballings and Mark Hyde, 2011-17
Bingham, M.G., Willemen, A., Wursten, B.T., Ballings, P. and Hyde, M.A.
. Flora of Zambia: Glossary details: corolla.
http://www.zambiaflora.com/speciesdata/glossary-display.php?glossary_id=166, retrieved 27 March 2017