Customers often ask us whether our aquarium plants are cultivated submersed (submerged, i.e. underwater) or emersed (emerged, i.e. above water). I can answer the question with a clear “it depends”. ?
What are submerged aquarium plants?
In nature, most of the plants suitable for aquaristics grow above water. So these are usually emersed plants. They thrive in swampy terrain or on the banks of bodies of water. However, these plants are able to develop underwater leaves in the event of permanent flooding and then continue to live submerged. However, they grow more slowly under the water surface and the leaves are more sensitive to mechanical stress. Only the actual aquatic plants are real submerged aquarium plants. They cannot live permanently emerged and are dependent on water as a habitat. These include, for example, the species of the genera Vallisneria, Myriophyllum, Cabomba, and the water lilies. But also the well-known hornwort (Ceratophyllum demersum) and waterweed (Egeria densa) always grow submerged in nature.
Why are the plants produced emersed and not submerged?
The production of emersed plants is significantly cheaper than rearing them underwater. Like all production companies, nurseries are also subject to enormous cost pressure. Heating and lighting costs have almost doubled in recent years. Many smaller nurseries had to give up or relocated their entire production to Asia.
However, some large and specialized nurseries in Holland, Germany, and Denmark have survived by consistently converting to emersed production processes, modernizing and automating their production. Today they supply high-quality aquarium plants from European production. However, all plants that only grow submerged are also bought here from Asia.
Do submerged plants grow better in aquariums than others?
https://youtu.be/JFOloB48ggU
No, because the corresponding plants are also adapted to changing water levels in nature. It is also a myth that they first lose all their leaves and then create new underwater leaves. Leaves that have grown above water also contribute to photosynthesis in the aquarium. However, if the plant remains under water for a longer period of time, it will in fact gradually develop better-adapted underwater leaves. The existing leaves are subject to the normal aging process and die off over a period of a few weeks to months.
In many genera, however, the submerged leaves differ fundamentally in appearance from those that have grown above water. The best example of this is the round-leaved Rotala. While the emersed leaves are round (Latin name!) and green, elongated, bright red to red-brown leaves grow under water. Of course, this looks strange at first a few weeks after planting. However, aquarists only use the tips of the shoots for propagation, so the plant only consists of submerged stems after the first regeneration at the latest.
A clear distinction between emersed and submerged aquarium plants using the example of Echinodorus xbarthii (Barth’s sword plant)
Another clear example of the different appearance of submersed and emersed specimens is the sword plants. The “air leaves” of sword plants look almost exclusively mottled green or green-brown. Underwater, on the other hand, the plants are transformed into colorful treasures. Bright red, purple, or flaming red leaves gradually emerge from the rosette. After a few weeks, the plant is no longer recognizable.
But not only the color of the leaves changes. While emersed echinoderms often have elliptical, ovate, or lanceolate leaf shapes, the leaves of submerged specimens are significantly narrower, often band-shaped or linear. Many varieties get slightly wavy leaf edges under water.
Many German names of our aquarium plants indicate the underwater forms. For example, if the aquarist has a “ruby red sword plant” in front of them that has grown in a greenhouse, then they sometimes ask themselves the question of the origin of the name. Only after a few weeks of aquarium culture does it become clear what the namesake had in mind.
