In epigeal germination, the sprouting seed leaves rise above ground level, while in hypogeal germination, seed leaves emerge from the seed and remain underground or at ground level. The seed leaves that emerge from the seed coat during germination are called cotyledons. Seed germination is the growth of a seed when exposed to adequate soil conditions, water and light.
In hypogeal germination, the cotyledons emerge from the seed containing enough nutrients to fuel seed development and are not photosynthetic. These seeds are usually larger than epigeal seeds. As the seedling grows, its shoot rises above ground level, while the cotyledons remain below or at ground level.
In epigeal germination, the cotyledons emerge and rise above ground level as the seedling grows. They may also serve a photosynthetic role in seedling development. Seedlings that develop this way quickly form a shoot and leaves, both of which perform photosynthesis to fuel further development.