Salvinia fern floating - a small plant floating on the surface of water bodies that belongs 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.
Salvinia floating: structure and appearance
This is an annual fern with a thin stem reaching fifteen centimeters in length and having whorls of three leaves on each node. The stem floats on the water surface. Its two leaves are whole, 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 holding air bubbles. This makes it possible for salvia to stay on the surface of the water. The third leaf is underwater, dissected into filamentous lobes covered with hairs and very similar in appearance to the roots. In fact, it just performs the functions of the roots: it absorbs water and nutrients, and also stabilizes the fern.
Life Cycle of Salvia Floating
At the base of the leaves under water, there are clusters of four to eight spherical soruses. Some of them contain macro- and microsporangia, and subsequently female and male gametophytes are formed from them. Each megasporangium forms four megaspores, but only one of them develops. Typically, sixty-four microspores are formed in one microsporangium.
As a rule, in the fall soruses fall and sink to the bottom of the reservoir. There they hibernate, and by spring, their shell is destroyed. Sporangia float to the surface of the water and germinate. After breaking through the wall, sporangia of the microspores form a male three-cell gametophyte, and then two spermatogenic and two infertile cells form from its two cells. Of these, each produces four sperm. Sprouting, the megaspore also breaks through the shell, forming a female gametophyte. Three archegonia are formed on it, but after fertilization only one of them develops.
Distribution area
Salvinia floating has a fairly wide range: it is common in water bodies in Africa, the temperate and tropical regions of Asia, as well as in the southern and central regions of Europe. In the Russian Federation, fern is mainly found in the south of the European part, in the Far East, in Western Siberia. Floating salvinia is common in bodies of water with slow flowing or stagnant water, especially often seen in the elders of large Russian rivers.
Application and meaning
On the surface of water bodies, this fern, as well as other types of salvins, forms dense thickets that block the access of light to the water body, which often leads to significant changes in the water body of environmental conditions. As a result, in many states, salvinia floating is considered a harmful plant. Nevertheless, this fern has useful properties: for example, its thickets serve as an excellent refuge for fish fry.
As previously noted, floating salvinia is cultivated as an aquarium plant. However, it is bred not only as a decorative element of a container where fish is kept, but also as a good natural shade for other plants that prefer diffused light.
