An embryonic leaf in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed.‘The cotyledons are the ‘seed leaves’ produced by the embryo.’
- ‘However, protein biosynthesis in the axis organs and cotyledons of dicotyledonous seeds commences much earlier.’
- ‘Mutants of this class display shortened hypocotyls and small cotyledons after irradiation of seed.’
- ‘They are present on the stems, leaves, cotyledons, rachises, pedicles, bracts and calyces.’
- ‘The layer between seed coat and cotyledon probably includes the wall of the embryo sac.’
Mid 16th century (denoting a patch of villi on the placenta of mammals): from Latin, ‘navelwort’ (which has cup-shaped leaves), from Greek kotulēdōn ‘cup-shaped cavity’, from kotulē ‘cup’.