Recreational users can easily spread these small fragments from waterbody to waterbody. However, hydrilla's real secret to success is its ability to produce structures called turions and tubers. They break free of the parent plant and drift or settle to the bottom to start new plants. Tubers are underground and form at the end of roots. They are small, potato-like, and are usually white or yellowish.
Hydrilla produces an abundance of tubers and turions in the fall.
Tubers may remain dormant for several years in the sediment. The hydrilla variety found in Washington will also make tubers in the spring and will produce nondormant turions throughout the growing season. Tubers and turions can withstand ice cover, drying, herbicides, and ingestion and regurgitation by waterfowl. There are two varieties of hydrilla in the United States. In New Zealand, where hydrilla has also been introduced, the hydrilla plants are all male.