S. americanus may refer to: * Samolus americanus, a water rose species * Schoenoplectus americanus, a bulrush species * , a lobster species in the genus Scyllarus * Siphonorhis americanus, a bird species * Spondylus americanus, an oyster species in the genus Spondylus * Styrax americanus, a snowbell species in the genus Styrax * Symbion americanus, a microscopic symbiote of the American lobster in the genus Symbion