The four leaf clover (Marsilea quadrifolia) is an archaic plant from the fern group. This plant is a sign for biotopes with a high level of cleanness.

This species of clover is vulnerable and it can be found only in the areas with remote lakes from the Danube's Delta and in the coastal area.
In order to develop properly, the four leaf clover needs an extremely clean environment.

The four leaf clover is a perennial and hemicryptophyte plant, with a height of 5 to 20 cm, which produces spores between August and October.

Polluted water is one of the main reasons why the population of four leaf clover has decreased.