Salvinia, also called Water Fern, is a small, aquatic fern that floats at the surface with a hairy root-like leaf dangling below. Floating leaves are in pairs, oblong to nearly round, about 0.4 to 0.8 inches in length. A third leaf is position below the water surface in place of roots. Floating leaves are bluish-green and covered with stiff hairs and bump-like projections. A crease usually runs down the center of each leaf. Giant Salvinia, S. molesta, has leaves 0.5 to 1.5 inches long. The leaves of young plants lie flat on the water surface; as the plants mature and form mats, the leaves are folded and compressed into upright chains. Giant Salvinia also differs from common salvinia, in having rows of cylindrical hairs on each leaf that are topped with 4 branches that arejoined at the tips to form a cage, giving the leaf a velvety appearance and allowing it to repel water. Common salvinia has leaf hairs that are not joined at the tips.