Sui generis
Sui generis (; ) is a Latin phrase that means "of its (his, her, their) own kind; in a class by itself; unique."
Sagittaria isoetiformis
Sagittaria isoetiformis, common name quillwort arrowhead, is an aquatic plant species native to Cuba and to the southeastern United States (Florida, Alabama, Mississippi, Georgia, North Carolina and South Carolina).