Neighbor influences and seasonal growth patterns for Vallisneria americana in a mesotrophic lake.

Biomass of the submersed macrophyte Vallisneria americana rose steadily from early June to 50 g dry wt·m in ealry August. Leaves dominated the biomass of this perennial from mid-June through August, after which plants senesced to leave only winter buds as perennating organs. Only 24% of plants sampled flowered during the 1978 growing season, yielding a population mean of less than 0.