Russian knapweed 
Sagebrush false dandelion 
Sand Sagebrush 
Santa Barbara Daisy 
Santa Maria Feverfew 
Sanvitalia procumbens 
Saw-tooth Sage 
Saw-Wort 
Scabland sagebrush 
Scentless False Mayweed 
Scorzonera alpigena 
Scorzonera eriophora 
Scorzonera libanotica 
Scorzonera meyeri 
Scorzonera mollis 
Scorzonera multiscapa 
Scorzonera papposa 
Scorzonera phaeopappa 
Scorzonera psychrophila 
Scorzonera rigida 
Scorzonera schweinfurthii 
Scorzonera syriaca 
Scorzonera tortuosissima 
Scorzoneroides cichoriacea