Dispersal by Water (Hydrochory)

Hydrochory is dispersal of seeds and fruits by water, and it is naturally most common among plants that grow in or near water bodies, where a passing current is a readily available transport mechanism. Adaptations for hydrochory generally revolve around buoyancy. Some fruits develop an obconical (inverted-cone-shaped) receptacle with large internal air spaces that keep the fruit afloat (e.g. Nelumbo, the lotus). Others rely on a fibrous mesocarp combined with a light pericarp — the coconut is the textbook example, its thick fibrous husk trapping enough air to keep the whole fruit buoyant across long ocean voyages until it washes ashore somewhere new. Some seeds are simply light and small and carry a specialised covering called an aril that traps air around the seed (e.g. Nymphaea, the water lily). Some whole fruits are inflated to increase buoyancy directly (e.g. Heritiera littoralis). And in some cases the seed itself would not float on its own, but is instead physically swept along …