Spotlight on Hydrilla verticillata
Hydrilla referred to as a “superweed” can grow as much as 6 inches a day!
Starting out as a popular aquarium plant in the 1950’s, Hydrilla , once released found an easy home in Florida. This non-native invasive aquatic plant is a perennial plant that flourished in warm southern waters but was also found to be tolerant of cooler more temperate waters further north. Hydrilla dies back to a bulb in the northern winter only to re-grow in the spring. It has spread to establish colonies in Canada, some Northeast states and California. Hydrilla out competes native vegetation crowding it out and replacing it until there is only one left – the Hydrilla.
Capable of growing to lengths more than 25 feet long it can reproduce multiple ways. It replicates through seeds, turions (buds that detach to grow a new plant), rhizomes, and tubers. New plants can also grow from stem fragments. It is reported that tubers can remain viable for up to 4 years and in optimum conditions can yield up to 6000 tubers per square meter. Hydrilla has a wide temperature and turbidity tolerance and has been found growing in the salty estuaries of Chesapeake Bay.
The plant can show variable appearance based on growing conditions but all plants have a whorled leaf of 5 or more leaflets. The leaf edges are serrated and have a central vein. Hydrilla can be easily confused with a native Elodea plant which has only three leaflets around a central whorl. The Hydrilla Hunt ID card has a side by side illustration and a way to report its discovery if it is found in Michigan. So far, no Hydrilla has been reported and no hydrilla colonies have been found in Michigan.
Hydrilla is one of the most invasive plants in the world and will form dense mats that can choke waterways and public water supplies. If this plant gets into Michigan waters there would be serious environmental and economic impacts. One way you can help prevent the spread of aquatic invasive species is to inspect your gear when ever leaving and before entering a body of water for any plant, mud or debris attached. Cleaning your boats, trailers, and other watercraft; your fishing and hunting gear and water sport equipment, including your pets if they swim in lakes is the first best prevention step we can take to make sure this and any other aquatic invasive species.
For more information about invasive aquatic plants contact Beth Clawson, MSU Extension Educator. To learn more about invasive organisms and invasive aquatic plants contact Michigan State University Extension Natural Resources educators who are working across Michigan to provide aquatic invasive species educational programming and assistance. You can contact an educator through MSU Extension’s “Find an Expert” search tool using the keywords “Natural Resources Water Quality.”