Radicula

Radicula is a botanical term derived from Latin, meaning "little root." In botany and plant embryology, radicula denotes the embryonic root of a seed plant—the part of the seed embryo that develops into the primary root upon germination. In a typical seed, the embryo consists of a radicle and a plumule; the radicle is located at the basal end and becomes the root that anchors the plant and begins water and nutrient uptake.

In dicotyledonous plants, the radicle emerges first during germination and enlarges downward, often protected by a root cap; it forms the primary root, from which lateral roots later arise. In monocots, the radicle may grow briefly or remain small, with the seedling sometimes relying on the coleorhiza and coleoptile before true roots develop.

Etymology: radicula is the diminutive form of Latin radix, meaning root; the modern English term radicle is more commonly used for the embryonic root, while radicula appears mainly in historical texts or in botanical Latin.

In usage, radicula is used to describe the seed embryo's root component and is sometimes encountered in anatomical descriptions of seeds, particularly in Latin or early English literature. The term should not be confused with mature roots or with the root system after germination, which is simply called the root.