When garden streams are introduced, unconnected with lake scenery, they are often intended to represent one or more of the six Tamagawa, or "Gem-rivers" of Japan. The Tamagawa near Tokio consists of rapid shallows occupying the centre of a wide pebbly bed, and the banks at its sudden bends are strengthened with piling and breakwaters formed of heaps of bamboo baskets containing stones. The artificial introduction of such features, bordering garden streams, and the planting of kerria and other river-side plants and grasses on the banks, assist in reproducing the effect of the natural scenery. Gardens with a river and no lake are often designed to represent some wild-moor scenery; the river should in such cases be given a broad channel.
