Aqueous extracts of peat‐like sediments from Lake Starvation, Hillsborough County, Florida, inhibit the growth ofHydrilla verticillatain laboratory systems. The extracts were obtained by autoclaving sediment in water, and it may be that this process degrades the sediment. Evidence is presented that the total organic content of the extract obtained is not substantially different from solutions obtained at much lower temperatures. Therefore, the use of autoclaving in the preparation of sediment extract would appear to produce a material similar to that possibly produced in the environments of selected lakes.