mesocotyl A shoot internode that is the part of an embryo axis or the stem of a seedling above the scutellum and below the coleoptile. Occurs in grasses. In grasses, the hypocotyl and cotyledon may not be visible and may be represented by the scutellar node and scutellum, making the mesocotyl similar to the epicotyl in other taxa. Elongation of the mesocotyl during seedling growth pushes the coleoptile above the soil surface. Catherine Leroy stem internode