Sea clubrush 
Sea oats 
Sea Rush 
Secale montanum 
Seersucker sedge 
Sharp-flowered Rush 
Short-fruit Rush 
Siberian Grass 
Sickle Grass 
Silver Hairgrass 
Silver Sedge 
Simplestem bur-reed 
Simplestem bur-reed 
Slender Clubrush 
Slender rush 
Slender Sedge 
Slim-stem small reed grass 
Slough sedge 
Small ballmoss 
Small Bushman Grass 
Smooth cordgrass 
Soft Brome 
Southeastern Wildrye 
Southern cattail