Hibernaculum is the term often applied to a winter bud of certain aquatic plant

Aquatic plant

Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...

s, such as the bladderwort

Bladderwort

Utricularia, commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species . They occur in fresh water and wet soil as terrestrial or aquatic species across every continent except Antarctica...

s (Utricularia

Bladderwort

Utricularia, commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species . They occur in fresh water and wet soil as terrestrial or aquatic species across every continent except Antarctica...

). The buds are heavier than water, and, being developed at the approach of cold weather, they become detached, sink to the bottom of the pond, and thus survive the winter. In the spring, they enlarge, developing air space

Buoyancy

In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

s, rise to the surface, and reproduce their species.

Certain temperate Sundews (Drosera) form Hibernacula as well, including Drosera filiformis

Drosera filiformis

Drosera filiformis, commonly known as the Thread-leaved sundew, is a small, insectivorous, rosette forming species of perennial herb. A species of sundew, it is unusual within its genus in that the long, erect, filiform leaves of this plant unroll in spirals - an arrangement similar to the...

, Drosera intermedia

Drosera intermedia

Drosera intermedia, commonly known as the oblong-leaved sundew or spoonleaf sundew, is an insectivorous plant species belonging to the sundew genus. It is a temperate or tropical species native to Europe, southeastern Canada, the eastern half of the United States, Cuba and northern South America.-...

, Drosera rotundifolia

Drosera rotundifolia

Drosera rotundifolia is a species of sundew, a carnivorous plant often found in bogs, marshes and fens...

and more.