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How are hypogeal and epigeal germination different in seed plants?

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Tall giant sequoia trees with reddish bark and thick trunks rise closely together in a dense forest at Sequoia National Park, California. — Tree A stand of giant sequoia trees (*Sequoiadendron giganteum*) in Sequoia National Park, California.

In seed plants, the primary difference between hypogeal and epigeal germination lies in whether the cotyledons (seed leaves) are carried above the soil surface during early development.12

Hypogeal Germination (Belowground)

In hypogeous germination, the hypocotyl remains short, causing the seed and its enclosed cotyledons to remain underground. The epicotyl elongates to push the shoot through the soil. Nutritional reserves are transferred from the cotyledons or endosperm directly to the developing radicle and epicotyl. Examples include the garden pea and garlic.12

Epigeal Germination (Aboveground)

In epigeous germination, the hypocotyl elongates significantly, raising the cotyledons, epicotyl, and seed coat above the soil. Once exposed to light, the cotyledons may either degenerate after transferring their stored nutrients (as in garden beans) or expand to become photosynthetic organs (as in castor beans).12