S. americanus

S. americanus may refer to:
 * Samolus americanus, a water rose species
 * Schoenoplectus americanus, a bulrush species
 * Scyllarus americanus, 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