Oct 31, 2013

Hydrilla verticillata found in lower Croton River

New York, NY

October 19, 2013

Hydrilla verticillata found in lower Croton River

On October 19th, 2013, as part of a New York Botanical Garden (NYBG) project studying plants of the intertidal reaches of the Hudson River, Principal Investigator Rob Nacz, Arthur J. Cronquist, Curator of North American Botany at NYBG, and David Werier, a Botanical and Ecological Consultant working on the project, found a population of Hydrilla verticillata in the tidal section of the Croton River, Westchester Co., New York (map below). The population was not inventoried but the plants are reported as being clearly well established. The population was observed about 0.8 and 1 km upstream from the mouth of the Croton River where it joins the Hudson River south of Croton Point. Many of the individual plants observed were non-rooted plants washed onto the shore; numerous rooted plants were also observed. Vegetative propagules, both above and below the substrate were observed and specimens were collected and returned to the NYBG. The Hydrilla was found in an area that is also populated with numerous rare plants, which will likely make control efforts more difficult than in other areas.

The finding has been tentatively confirmed by the NYS Department of Environmental Conservation; additiional results to determine whether the population is monoecious (a plant having both the male and female reproductive organs in the same individual), or dioecious (plants which produce a male plant and a female plant and not usually a single plant with both male and female parts). Hydrilla's dioecious form is found mainly in the southern U.S.; north of South Carolina Hydrilla is mainly monoecious. The Croton finding is believed to be monoecious. Additional information will be posted here as an update as soon as final determination is made.

An interagency response team was established under the direction of NYS DEC on November 8th. Participating in the early response meeting were representatives from: DEC Central (Albany) Office; DEC Region 3; the Hudson River Esturary Program; DEC's Invasive Species Coordination Unit; DEC's Divisions of Lands & Forests and Water; the NYS Invasive Species Database (iMapInvasives); the NYS Invasive Species Clearinghouse; Cornell Cooperative Extension; the Lower Hudson Partnership for Regional Invasive Species Management; the NYC Department of Environmental Protection; the US Army Corps of Engineers; and the Cayuga Lake Hydrilla Task Force. More information on response planning will be posted on this site in the near future.

For more information, contact:

Wendy Rosenbach (NYSDEC)

Click on map to enlarge.