Stratiotes aloides

Stratiotes aloides, commonly known as the water soldier, bears dense vegetation in a rosette of stiff and prickly leaves that rises to the surface of the water when flowering. This perfectly hardy and prolific perennial is appreciated for its purifying and oxygenating properties in calm, non-calcareous waters, with a depth ranging from 30cm (12in) to 1 m (3ft), exposed to sunlight. It also provides a good shelter for many insects and fish. After flowering, in autumn, it sinks to the bottom of the water to spend the winter sheltered from the cold, waiting for the next spring. It is a beautiful, unique, useful, and easy-to-grow leafy plant.

Stratiotes aloides belongs to the Hydrocharitaceae family. It is widely spread in Europe and northern Asia. It is found in calm, non-calcareous waters, at a maximum depth of 1m (3ft). It forms an upright rosette-shaped clump, composed of linear, lanceolate, pointed, incurved, dark olive-green leaves, reaching 40cm (16in) in length and 5 to 15mm (1in) in width, with spiny margins. In spring, the fully submerged clump roots itself in the mud. Its vegetation reaches up to 40cm (16in) in all directions. In late spring, it rises to the surface for flowering and loses its roots. Only the heart of the plant remains underwater, and the whole plant freely moves on the surface. From May to July, it produces a few flowering stems that display simple flowers, 2 to 3cm (1in) in diameter. These cup-shaped blooms are white or pink with sulphur-yellow stamens.

Plant it in a pond or a lake by placing it directly on the water surface. Position it in the sun, in calm waters with acidic clay mud as the substrate. Perfectly hardy, it can be grown in all regions and can even become invasive. It is a stemless perennial that mainly reproduces through stolons, producing identical seedlings that are easy to separate from the mother plant. Divide it as soon as it becomes too prolific. However, this aquatic plant does not tolerate high temperatures, so it should not be installed in waters with a temperature that can exceed 22°C (71.6°F). 

Stratiotes aloides is an oxygenating and purifying plant whose dense root network efficiently absorbs nutrients in nutrient-rich waters and limits the growth of algae. It also provides an interesting habitat for hosting the eggs of many aquatic insects and fish.