Hydrilla
Hydrilla verticillata

Origin: Central Africa

Background
Hydrilla first appeared in the Crystal River system of Florida in 1960. Imported by the aquarium trade, its presence on the Delmarva Peninsula was confirmed in 1981. Hydrilla attracted national attention when infestations were found in the Potomac River in Washington, D.C. in the early 1980s.

Description
Rooted aquatic plant; a member of the frogbit family (Hydrocharitaceae). Leaves up to 3/4 inch long; usually in whorls of five oblong leaves on the stems; fine teeth visible to the naked eye on leaf edges and mid-ribs. Tiny, translucent to white flowers produced on the upper branches in late summer and fall; tubers grow from the roots; winter buds (turions) are produced in the leaf axils. Spreads vegetatively through fragments of stems, stolons, or rhizomes, turions, or tubers which are carried on boat livewells, motors and trailers, bait pails and other items, and by ingestion of tubers and turions by waterfowl.