24. Nov 2015
Time spent out of water provides strength for life under water. In the wild, nine out of ten tropical aquarium plants are capable of surviving both above and below the water surface.
They are known as amphibious plants – plants which can adapt to long dry periods above water when the water level in rivers and streams drops. They actually make good use of the time with the sun shining on the damp, nutritious soil which once was a river bed, gathering strength for the underwater existence which will follow when the rainy season returns.
The length of time the plants spend above and below water can vary considerably, but the pattern is always the same. Many plants transform in order to take the greatest possible advantage of conditions in the open air. Some develop completely new leaf shapes and colours, so that they can make the best of the light. Many of them flower and seed. Most of them develop new side shoots, which not only ensure further propagation, but also that a greater reserve of nutrition is built up for the time under water.
Plants with improved adaptability
Some people claim that all aquarium plants should be cultivated under water. But at Tropica we have discovered that plants that are amphibious in the wild adapt more quickly and easily to conditions in an aquarium if they are cultivated above water.
At Tropica we simulate the conditions prevailing in the tropical dry season throughout the growth of the plant. Only the roots are under water - planted in mineral wool in pots. The temperature and humidity in the greenhouses are controlled electronically so the climate is identical to that of a tropical rain forest, and powerful artificial light is provided above our growing tables to compensate for the short daylight hours in Denmark from September to March. The plants gather their strength and energy prior to spending a period under water just as they do in the wild. The light conditions, water hardness, pH value and EC value are rarely identical from one aquarium to the next. But a Tropica plant cultivated in emerse conditions always has the reserves and surplus energy needed to develop new leaves capable of flourishing in its new environment. If the same plant is cultivated under water it adapts to the water conditions prevailing in the nursery. It does not build up special reserves because it is already under water. So it finds it harder to adapt to a new aquatic environment. Some plants (e.g. Egeria, Cabomba and Vallisneria) are pure water plants. They are only found in the wild growing under water, so naturally Tropica cultivates these plants submersed in large tanks