Hydrilla has pointed, bright green leaves about 5/8 inches long. The leaves grow in whorls of 3 - 10 along the stem, 5 being most common. The margins of the leaves are serrated (toothed). Thin stalks from the stem end in a single, small, floating white flower at the water's surface. A key identifying feature is the presence of small (up to half inch long), dull-white to yellowish, potato-like tubers which grow 2 to 12 inches below the surface of the sediment at the ends of underground stems. These tubers form at the end of the growing season and serve to store food to allow Hydrilla to overwinter.
- Langeland, K. A. 1996. Hydrilla verticillata (L.F.) Royle (Hydrocharitaceae), "The Perfect Aquatic Weed". Castanea 61:293-304.
- Menninger, H. 2011. Hydrilla verticillata in the Cayuga Inlet: A science‐based review to guide management actions. NY Invasive Species Research Institute, Cornell University, Ithaca, NY. 11 pp.