What plant structure terminates the radicle (embryonic root)?

The structure that terminates the radicle, or embryonic root, is the root cap. The root cap is a specialized tissue found at the tip of the root, which protects the growing tip as it pushes through soil or other growing media. It also plays a crucial role in the perception of gravity and direction of growth, guiding the root downwards into the soil.

The cotyledon is the first leaf or leaves that appear from the seed of a plant; while it is essential for the initial energy supply of the seedling, it does not have a role in terminating the radicle. The hypocotyl, which is the stem-like structure that connects the radicle to the cotyledons in germinating seeds, is involved in lifting the plant up as it grows, but it is not the terminal structure of the radicle itself. The epicotyl is the part of the stem above the cotyledons and is responsible for the growth of the true leaves and floral buds, so it is distinctly different from the root terminus.

Hence, it is the root cap that directly terminates the radicle, providing protection and helping navigate the soil environment, which is vital for proper root development and overall plant stability.