part of leaf morphogenesis embryonic morphogenesis cotyledon development cotyledon morphogenesis The process in which the anatomical structures of the cotyledon are generated and organized. The cotyledon is the modified leaf (seed leaf), found as part of the embryo in plant seeds. It is involved in either storage or absorption of food reserves. Dicotyledonous seeds contain two cotyledons, while monocotyledonous seeds contain only one. The cotyledons may appear above ground and show photosynthetic activity in the seedling. GO:0048826 biological_process post-embryonic plant morphogenesis