plúmula

Plúmula, in botany, is the part of the embryonic plant that develops into the shoot system after germination. In most seeds, the plumule is the portion of the embryo located above the radicle, and it contains the shoot apical meristem and developing leaf primordia. The plumule is distinct from the radicle, which forms the root, and from the cotyledons, which are seed leaves that often function as nutrient sources during germination.

Etymology: The term plúmula derives from Latin plumula, a diminutive of pluma (“feather”), reflecting historical imagery of a small, feathery shoot.

In monocots, such as grasses, the plumule is typically enclosed by the coleoptile, a protective sheath, and emerges only after the coleoptile ruptures; the first leaves arise from the plumule as germination proceeds. In dicots, the plumule includes the shoot apex and early leaf primordia that expand to form the epicotyl, stems, and true leaves.

Function and significance: The plumule constitutes the embryonic shoot and controls the initiation of the above-ground plant parts. Its proper development is essential for successful germination and establishment of the seedling.