The pistia is a floating perennial plant native to the American continent. Its common name, aquatic lettuce, suggests its shape, in fact the tufts of pistia are very similar to heads of lettuce, whose leaves are however thick, slightly spongy and with serrated edges, covered by a thick and soft down and have deep veins . From the tufts branch off long blackish roots, which hang below the tufts that float freely along the water courses. In spring in the center of the rosette of leaves bloom small whitish, insignificant flowers. The plants of pistia they tend to widen and to form large colonies, which cover the entire surface at their disposal, for this reason we advise against "freeing specimens of pistia in waterways and lakes, where they could cause environmental problems.
The aquatic lettuce prefers the sunny positions, but it develops without problems even in areas that are placed in partial shade. It does not fear the cold very much, but very cold temperatures and above all frost can irreparably compromise the pistia specimens; for this reason, in the places where the winter minimum falls below zero, it is advisable to transfer the plants of these varieties to a protected place by placing them in a container or in a tank full of water, a fundamental condition for the pistie to survive the better.
This variety of plant, of aquatic genus, floats completely on the surface of the water, therefore it is not affected by the type of soil that constitutes the bottom of ponds and small ponds. To put it down it is sufficient to place it on the surface of the water. It is advisable to add to the water of our basin a specific fertilizer for aquatic plants, to avoid unsightly yellowing of the leaves. If there are fish or plants in the pond for which the fertilizer would be harmful, it is advisable to periodically remove the pistia specimens, and place them in a basin filled with water and fertilizer for aquatic plants, in order to supply the plant with all the nutrients it has need to rearrange the plants in the water.
As far as the multiplication of aquatic lettuce is concerned, it is good to know that this kind of plant naturally develops numerous plants "daughters", attached with long aerial roots to the stole of the "mother" plant; in spring it is possible to take the daughter plants to get new specimens, even if the tracks are usually left to develop freely and the excess specimens are taken only when they are too numerous and you want to transport them elsewhere or eliminate them. The slopes also produce small green berries containing some seeds, which must be rooted in a container filled with water or gelatine for hydroculture. In this case, if one proceeds starting from the seeds, the new specimens must be kept in a sheltered place for at least two years before being planted.
Aquatic lettuce - Pistia: Pests and diseases
This variety of aquatic plant has a rustic and resistant character and, for this reason, does not fear pests or diseases. Therefore, it is not necessary to proceed with preventive pesticide treatments.