The other soil factor that must be taken into consideration is continuous moisture, that is, soils that are continuously saturated. The majority of trees will not grow in these conditions, but those that will include the numerous kinds of willow (Salix), large and small, as well as the alders (Alnus), which are mostly trees of moderate size. The handsome and uncommon swamp cypress, Taxodium distichum, is also good, though very wet conditions are not necessary for its success.