Merriam-Webster Collegiate Dictionary - saw palmetto

 noun  Date: 1797  1. any of several shrubby palms chiefly of the southern United States and West Indies that have spiny-toothed petioles; especially a common palm (Serenoa repens) of the southeastern United States with a usually creeping stem  2. a preparation derived from the berrylike fruit of a ~ (Serenoa repens) that is held to have a therapeutic effect on the prostate gland and is used in dietary supplements and herbal remedies