plumule

Growth of the plumule does not occur until the cotyledons have grown above ground.

These seeds develop by the plumule growing up through the soil with the cotyledons remaining below the surface.

The plumule is the baby shoot.

However, in seeds such as the broad bean, a leaf structure is visible on the plumule in the seed.

In most seeds, for example the sunflower, the plumule is a small conical structure without any leaf structure.

The radicle is the embryonic root of the plant, and grows downward in the soil (the shoot emerges from the plumule).

It involves the reactivation of the metabolic pathways that lead to growth and the emergence of the radicle or seed root and plumule or shoot.

Some plants like Peony species have multiple types of physiological dormancy, one affects radicle (root) growth while the other affects plumule (shoot) growth.

A mesocotyl-that part of the young plant that lies between the seed (which remains buried) and the plumule-extends the shoot up to the soil surface, where secondary roots develop from just beneath the plumule.

Sixty days after germination the transfer of reserved from the seed has been completed, but it is only after 80 or 90 days that the young shoot (the plumule) emerges from the cotyledon.

Gymnosperm seedlings also have cotyledons, and these are often variable in number (multicotyledonous), with from 2 to 24 cotyledons forming a whorl at the top of the hypocotyl (the embryonic stem) surrounding the plumule.

The plumule is an embryo shoot with a hypocotyl stem structure below the point where the plumule was attached and an epicotyl stem structure above this attachment point.

After emergence of the radicle, the hypocotyl emerges and lifts the growing tip (usually including the seed coat) above the ground, bearing the embryonic leaves (called cotyledons) and the plumule that gives rise to the first true leaves.

The plumule gives rise to the first leaves of the plant that will go on to grow into organs for transpiration, with the opening and closing of the stomata found within the cell structure of leaves; for photosynthesis, and for other metabolic activities.

The seeds of corn are constructed with these structures; pericarp, scutellum (single large cotyledon) that absorbs nutrients from the endosperm, endosperm, plumule, radicle, coleoptile and coleorhiza-these last two structures are sheath-like and enclose the plumule and radicle, acting as a protective covering.