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Why does the root emerge first when a tree seed germinates?

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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.

When a seed germinates, the primary root—or radicle—typically emerges first to establish the plant's foundation in the soil. This early growth is driven by cell expansion and division, allowing the radicle to anchor the seedling and begin the essential process of nutrient and water uptake.12

The radicle is positively geotropic, meaning it responds to gravity by growing downward into the earth. This orientation is critical for the plant's survival, as it secures the seedling and provides the necessary stability for the subsequent emergence of the shoot, or plumule. While the radicle moves toward the soil, the shoot is negatively geotropic, growing upward to seek light for photosynthesis.12

Although the root usually emerges first to ensure the plant is properly anchored and hydrated, there are exceptions; for example, in the coconut, the shoot may emerge before the root.12