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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Publications at this Location » Publication #424508
Research Project: Integrated Weed Management and Restoration Strategies to Protect Water Resources and Aquatic and Wetland Ecosystems of the Far Western U.S.

Location: Invasive Species and Pollinator Health

Title: Growth patterns of three Hydrilla verticillata biotypes in the United States

Author
item Beets, Jens
item FOLEY, KARA - North Carolina State University
item SPERRY, BENJAMIN - Us Army Engineer Research And Dvelopment Center
item HOWELL, ANDREW - North Carolina State University
item RICHARDSON, ROBERT - North Carolina State University

Submitted to: Aquatic Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2025
Publication Date: 7/17/2025
Citation: Beets, J.P., Foley, K.J., Sperry, B., Howell, A.W., Richardson, R.J. 2025. Growth patterns of three Hydrilla verticillata biotypes in the United States. Aquatic Botany. 201. Article 103294. https://doi.org/10.1016/j.aquabot.2025.103924.
DOI: https://doi.org/10.1016/j.aquabot.2025.103924

Interpretive Summary: A third, genetically distinct strain of hydrilla has been identified in the US. This strain of hydrilla belongs to a different clade (clade C) compared to the other biotypes in the US and very little is known about its growth and life history. This research examined growth and life history over two years in two distinct environments, one similar to its current range and one representing the southeastern US and warmer climates. The results of this two year study revealed that the clade C hydrilla had similar life history and biomass production to the other hydrilla biotypes. Notably, the clade C hydrilla produced axillary turions at a drastically higher rate than monoecious and dioecious hydrilla

Technical Abstract: Hydrilla ([Hydrilla verticillata (L.f. Royle)]) is an invasive perennial submersed plant that has been documented in the United States since the 1950s. Historically, there have been two strains of hydrilla, hereafter referred to as biotypes, recorded in the United States, both belonging to the same clade and have been characterized as ‘monoecious’ and ‘dioecious’. Recently, a third genetically distinct biotype was identified in the Connecticut River, CT. Plants were established in Raleigh, NC and Laurel Springs, NC and periodic harvests were performed. No significant differences were observed in peak aboveground biomass, relative growth rate or timing of these metrics between the three hydrilla biotypes, although the predicted peak biomass for dioecious hydrilla did not occur during the study period. Surprisingly, monoecious hydrilla had lower peak belowground biomass than dioecious and clade C hydrilla despite its abundant subterranean turion production. Monoecious hydrilla exhibited 1.74x greater aboveground biomass and 4.7x more subterranean turions 180 days after planting than clade C hydrilla. Clade C hydrilla produced 73.8 axillary turions per plant 180 days after planting compared to 32.8 axillary turions produced by monoecious hydrilla and 1.2 axillary turions produced by dioecious hydrilla. This research suggests the newly documented biotype of hydrilla in the Connecticut River has many similarities to the other two biotypes in the United States, but further research is needed to better understand the phenology and ecology of this invasive plant.