alkaline water conditions (they do not like very acidic conditions) and do not require carbon dioxide fertilization. They are also among the few commonly traded aquarium plants that tolerate brackish water, provided the specific gravity does not exceed 1.003 (around 10 percent the salinity of normal sea water). Species Accepted species Gallery References Further reading Systematics of Vallisneria (Hydrocharitaceae). Donald H. Les, Surrey W. L. Jacobs, Nicholas P. Tippery,1 Lei Chen, Michael L. Moody, and Maike Wilstermann-Hildebrand Systematic Botany (2008), 33(1): pp. 49–65 Hydrocharitaceae Hydrocharitaceae genera Freshwater plants Dioecious plants