Sickle Grass 
Silver Hairgrass 
Slim-stem small reed grass 
Small Bushman Grass 
Smooth cordgrass 
Soft Brome 
Southeastern Wildrye 
Spartina bakeri 
Sphenopus divaricatus 
Spreading Liverseed Grass 
St. Augustine grass 
Stalked Bur Grass 
Stipa arabica 
Stipa lagascae 
Stipa parviflora 
Stipa tenacissima 
Stipagrostis drarii 
Stipagrostis hirtigluma 
Stipagrostis raddiana 
Stipagrostis scoparia 
Sugarcane 
Swamp Foxtail 
Sweet Vernal Grass 
Taeniatherum caput-medusae