Salvinia floating fern is a small plant floating on the surface of water bodies belonging to the Salviniev family. This type species of the genus Salvinia is the only one growing on the territory of the Russian Federation. The plant is often cultivated as an aquarium plant.
Salvinia floating: structure and appearance
This is an annual fern with a thin stem, reaching fifteen centimeters in length, with a whorl of three leaves at each node. The stem floats on the water surface. Its two leaves are entire, have an ovoid-elliptical shape and a slightly heart-shaped base. They are covered on top with warts, which at the tops contain a bunch of thick short hairs. The lower surface of the leaves has a dense cover of brown hairs that hold air bubbles. This allows salvinia to stay on the surface of the water. The third leaf is submerged, dissected into filamentous lobes covered with hairs, and very similar in appearance to roots. In essence, it just performs the functions of the roots: it absorbs water and nutrients, and also stabilizesfern.
Life cycle of salvinia floating
At the base of the leaves, which are under water, there are clusters of four to eight spherical sori. Some of them contain macro- and microsporangia, and subsequently female and male gametophytes are formed from them. Each megasporangium produces four megaspores, but only one of them develops. Usually sixty-four microspores are produced in one microsporangium.
As a rule, in autumn, sori fall and sink to the bottom of the reservoir. There they hibernate, and by spring their shell is destroyed. Sporangia float to the water surface and germinate. After breaking through the wall of the sporangium, the microspores form a male three-celled gametophyte, and then two spermatogenic and two sterile cells are formed from two of its cells. Of these, each produces four sperm. Germinating, the megaspore also breaks through the membrane, forming a female gametophyte. Three archegonia are formed on it, but only one of them develops after fertilization.
Distribution area
Salvinia floating has a fairly wide range: it is common in the waters of Africa, temperate and tropical regions of Asia, as well as in southern and central Europe. On the territory of the Russian Federation, the fern is mainly found in the south of the European part, in the Far East, in Western Siberia. Salvinia floating is common in reservoirs with slowly flowing or stagnant water, especially often it can be seen in the oxbow lakes of large Russian rivers.
Use and meaning
On the surface of reservoirs, this fern, like other types of salvinia, forms dense thickets that block the access of light to the water body, which often leads to significant changes in environmental conditions in the reservoir. As a result, in many states, Salvinia floating is considered a harmful plant. Nevertheless, this fern also has useful properties: for example, its thickets serve as an excellent refuge for fish fry.
As mentioned earlier, Salvinia floating is cultivated as an aquarium plant. However, it is bred not only as a decorative element of the tank where fish are kept, but also as a good natural shade for other plants that prefer diffused light.
Fern content
It is best to place floating Salvinia in moderately warm or tropical aquariums. The plant does not impose special requirements on the conditions of detention. For him, neither the hardness of the water nor the acidity matters - both in soft and hard water, the fern grows equally well. The temperature in the aquarium should be maintained at a minimum of 24 degrees Celsius. If the water is only warmed up to 20 degrees, the growth of the plant will slow down (the leaves will become smaller), but will not stop completely.
If you have Salvinia floating in your aquarium, you should regularly change the water. As devices for artificial lighting of the reservoir, it is recommended to use phytolamps havingpower from three watts per liter, and fluorescent lamps. If you use incandescent bulbs, then make sure that their power is low, otherwise you can dry out the air.
