Limnobium laevigatum - Smooth frogbit

Limnobium laevigatum, is an aquatic perennial floating plant with oval leaves reminiscent of water lilies. It forms rosettes of leaves that float on the water's surface. Filtering and oxygenating, it also helps stabilise pond banks with its dense root system. Well adapted to regions with mild winters due to its hardiness, it is installed in full sun in marshy areas and shallow, calm waters. It should be noted that since its introduction to Europe, the invasive potential of this species has been observed.

Limnobium laevigatum belongs to the Hydrocharitaceae family. This species is native to freshwaters in Central and South America. In California, it was introduced as an ornamental pond plant and escaped into larger waterways. It is an invasive species in Chile. Frogbit can be confused with water hyacinth (Eichornia crassipes) due to their superficial resemblance. A distinctive characteristic of the young plant is the presence of spongy aerenchyma tissue on the lower surface of the leaf. Mature plants reach a height of 50 cm and have emergent leaves carried by petioles that are not swollen or inflated. Limnobium laevigatum can be distinguished from Limnobium spongia by leaf characteristics. The latter generally has more cordate floating leaves, while Limnobium laevigatum has more spatulate leaves. The leaf coloration is dark green, punctuated with reddish-brown on the upper surface and purplish on the lower surface. The leaves float on the water or stand upright in dense vegetation if the plant is on a bank. The lamina measures from 2 to 7 cm. Young leaves are shiny, bright green, and reddish underneath. Insignificant small flowers appear in summer and autumn in natural environments.

Whilst beneficial for ponds, it should be reserved for closed and artificial ponds to prevent its proliferation in open environments. This perennial should be planted in marshy areas, shallow stagnant waters, or waters with a weak current. It thrives in full sun or with good brightness.