Aquatic plants are commonly available in most aquarium stores and can generally be divided into two types: Emergent and submerged. These two terms are defined by the way we grow these plants within the aquarium setting.
In nature, the plants that we call aquarium plants most likely do not live 100% beneath the water surface. While there are some plants that do, it is much more common to find our favourite plants living on land along the shoreline of lakes, rivers, streams and wetlands and exposed to natural sunlight, collecting nutrients via their root systems and substrate. Many of these locations will flood from time to time which will force the plants into a fully aquatic setting for short periods of time. However, the majority of the year will see only their roots set underwater.
This is something that is very common in low flood plains, where plants will spend several months below the water's surface. While there are undoubtedly benefits to being underwater, this setting does expose plants to the many pollutants found in natural waterways. Of course, in nature, things are always different and what works in the wild does not always work in the aquarium. It is not practical for us to change the water level all the time so we must choose our plant species according to the layout and style of the aquarium we are planning.
The main difference between these two categories can easily be explained. Emergent plants grow above the surface of the water, while submerged plants grow below the water surface There is normally a difference in sale price too. It is costly to create conditions suitable to grow submerged plants. Additionally, growing emergent plants is a quicker process that reduces the cost and results in a lower sale price.
First of all, let us clear up a common misconception.
"Plants grown above water adapt worse in an aquarium than plants that are grown underwater."
Usually, when plants from emergent cultivation are placed underwater. The plant's original leaves (produced in terrestrial conditions) will melt. If the aquarist does not know this process, then she/he will most likely remove the plant thinking that their new plant has perished. However, it is worth waiting for this situation to play out. Patience is an aquascapers secret weapon.
This process takes time and we should always expect some leaves to melt away during this process. New leaves will appear. The newly released underwater leaves usually have a slightly different colour. Round leaves are also commonly produced underwater too. This is entirely normal. It means that the plant adapts the anatomy of the new leaves to different environmental conditions.
Depending on the type of plant - adaptation takes various forms.
- Stem plants (Rotala, Ludwigia, Limnophila, Myriophyllum) adapt to the underwater conditions without any problems.
- Plants of the genus Hygrophila, Alternanthera adapt longer than the above. When grown in low light conditions, it will lose leaves close to the substrate.
- Plants of the genus Cryptocoryne (applies to both emergent and submerged plants) will in most cases lose their leaves (Also known as 'Cryptocoryne Disease'). You should then cut the diseased leaves, leaving only the rhizome behind - in the next few days, new leaves will grow out of them, adapted to the conditions in the aquarium.
- Plants of the genus Echinodorus adapt to the conditions in the aquarium depending on the species (colourful artificial hybrid strains adapt more difficult) - most often it is manifested by a mesh on the surface of the leaves and ultimately the death of the entire leaf blade. In the next few days, new leaves will grow from the rosette, adapted to the conditions in the aquarium
- Plants of the genus Microsorum, Anubias - adapt to the aquarium without any problems.
All the above examples are based on providing the plants with the relevant conditions for growth With adequate lighting power (minimum 0.4W / l for smaller aquariums), with soft-medium hard water and pH 6.5-8, fertile soil and carbon dioxide. The provision of CO2 can greatly increase your plant's recovery time also. We must take into account that all plants originally grown in emergent conditions have had access to unlimited atmospheric Carbon Dioxide so when they are placed underwater, we should provide CO2 to assist in this transition.
Unlike underwater plants, emersed forms available in stores are more durable.
- They grow in natural light, so they have a fast metabolism and appropriate levels of enzymes and plant hormones, not limited by the availability of nutrients in the water.
- As they were grown above the water, they have more sturdy stems, thanks to which they are capable of withstanding the transportation environment - especially transport to pet stores and then the final receiver.
- They have a considerable amount of stored nutrients compared to underwater forms, thanks to which they more easily withstand unfavourable conditions in the aquarium during the process of adaptation to underwater conditions.
- They are free from waterborne diseases and parasites.
- They are free of spores of hard-to-remove algae and cyanobacteria.
In conclusion, below we present the most common mistakes contributing to the myth and problems with plant adaptation:
- Removing plants from the aquarium without patiently waiting for new leaves to develop.
- Planting plants in the sterile ground (clean gravel).
- No proper filtration in the aquarium.
- Lighting up too short (e.g. 4h) or too long (e.g. 18h) per day.
- No CO2 dosing when the fish stock is little.
- No regular water changes.
- Inadequate water parameters for plants.
It is absolutely possible to maintain an aquarium with both emersed growth and submerged and emergent growth. By making use of the quality substrate, nutrients, lights, CO2 injection and clever planning, the modern aquascaper can enjoy a beautiful display including all kinds of plants. Additionally, when correctly established, it can be extremely satisfying to watch these species produce flowers naturally. One example of an aquarium style that includes a blend of both submerged and emerged growth is the shallow pond style aquarium. This design pulls together both categories to create a very natural display.