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Name derivation:


Stems elongate (more than 3 cm), erect; leaves cauline, whorled.  Leaves with “prickles” along abaxial surface of midvein; leaf scales (“intravaginal squamules”) fringed with orange-brown hairs.

Hydrilla stems are slender, branched and up to 25 feet long. Hydrilla's small leaves are strap-like and pointed. They grow in whorls of four to eight around the stem. The leaf margins are distinctly saw-toothed. Hydrilla often has one or more sharp teeth along the length of the leaf mid-rib. Hydrilla produces tiny white flowers on long stalks. It also produces 1/4 inch turions at the leaf axils and potato-like tubers attached to the roots in the mud (Center for Aquatic and Invasive Plants).

Similar genera:

Elodea, Egeria


Freshwater lakes. "Invasive," introduced into Florida (USA) in 1960, from India or other countries bordering the Indian Ocean, where a tale of intrigue surrounds "Agent 0".  Apparently first identified by Bob Blackburn and Lyle Weldon in the Reflecting Pool and a pool in the Constitutional Gardens of Washington DC.  Hydrilla verticillata has now spread to 33 states (Fincham 2009). It is present on every continent except Antarctica (Langeland and Cherry 2008).




Center for Aquatic and Invasive Plants. University of Florida, IFAS Extention.online


Fincham, M.W.  2009.  Travels with Hydrilla: The unnatural history of an accidental invader. Chesapeake Quarterly 8(2). Also online.

Langeland, K.A., and H.M. Cherry, et al.  2008.  University of Florida-IFAS Publication SP 257.