Plants have attractive foliage and are planted in aquaria which are often emptied into freshwater habitats. Canadian elodea, Waterweed. Stems are ascending and usually are sparsely branched until the plants near the water surface and then become profusely branched. Stems can be up to 8.5 m long and grow to the surface of the water where the branchlets extend horizontally. Leaf margins are serrate, the teeth visible to the naked eye.
Fresh leaves are notably rough to the touch.
The midrib on the upper surface is often tinged with red and on the lower surface, usually has 1-celled sharp teeth or spines. Male flowers are solitary, small, on short stalks in the leaf axil and break off as buds, opening explosively on the water surface. Leaves mostly in whorls of four at sterile nodes, leaves 1.4 to 2.5 cm long Egeria densa . Plants grow in canals, springs, streams, ponds, lakes and reservoirs. Most populations of hydrilla in the United States are dioecious.