Epigeális

Epigeális (epigeal germination) is a form of seed germination in which the seed leaves, or cotyledons, are carried above the soil surface after germination. The process begins when the hypocotyl elongates, lifting the seed and causing the seed coat to rupture. The cotyledons then expand above ground and often become photosynthetically active, supplying energy to the seedling until true leaves develop.

In contrast, hypogeal germination keeps the cotyledons below the soil surface; the shoot apex and developing leaves emerge while the cotyledons remain underground, typically protected by the seed coat and soil.

Epigeal germination is common among many dicotyledonous plants. Typical examples include beans (Phaseolus species), peas (Pisum sativum), castor oil plant (Ricinus communis), cotton (Gossypium), and sunflower (Helianthus annuus). The trait can be influenced by environmental conditions such as light, temperature, and moisture, and it may be associated with seed size and stored reserves that enable the cotyledons to be raised above ground.

Ecological and agricultural significance includes enabling a rapid start to photosynthesis and accelerated seedling growth, which can be advantageous in light-rich environments. However, exposing cotyledons above soil increases vulnerability to desiccation, grazing, and herbivory before the true leaves establish. In farming, the germination type informs sowing depth, irrigation practices, and post-emergence protection strategies to ensure successful seedling establishment.