Giant salvinia

Floating Leaf Plants

Salvinia molesta:

Giant salvinia

Salvinia molesta Mitchell: Giant salvinia, kariba-weed, water spangles. Salviniaceae (water fern family). 

Exotic perennial. This plant is a small, oval-leaved fern that floats on the surface of the water; in spite of its small size it can produce extreme water-use problems by reproducing rapidly and creating dense mats to 3 ft (90 cm) thick. Individual, uncrowded, plants consist of two floating leaves and one underwater leaf that looks like a feathery root. The paired floating leaves are small, 0.5 - 1 in (1.25 - 2.5 cm), oval, with a shallow notch at the base and a distinct incised midvein along which the leaf may fold inwards as plants become more crowded. The dense hairs that cover the upper surface of the leaves split into several divisions at their ends and then fuse back together, forming a small sphere of filaments at the tip of each hair; these can be usually be seen without magnification. As colonies expand and become denser, plants produce leaves crowded alternately along a short hidden stem. Small, round, brown, seed-like sporocarps may be produced from underwater parts. Salvinia is a major long-term weed problem in many parts of the world, now being faced in the U.S.