Closely resembles the non-invasive Elodea. Hydrilla is popular with the aquarium and nursery industry.
Ecological Threat: Dense underwater stands of hydrilla raise water pH and temperature, and lower dissolved oxygen. While the total number of fish often increases, large fish become rare. Promotes mosquito habitat. Potentially affects power generation by clogging dams.
Biology & Spread: Reproduces from fragmented stems. New shoots also bud from leaf axils and underground tubers. Hydrilla can grow up to 1 inch in a day and stems can reach 30 feet in length. Stems grow until they reach the water surface, filling the entire water column.
Threat in Oklahoma: Hydrilla can take over lakes, rivers, reservoirs, ponds, and ditches, forming monoculture stands that can cover hundreds of acres. Known infestations in Oklahoma are in Lake of the Arbuckles, Lake Murray, and Sooner Lake. Good boat cleaning practices will help limit the future spread of within the state.