Softstem Bulrush      

Sorghum      

Southern Catalpa      

Southern Waternymph      

Southwestern Waterwort          

Sowthistle          

Spear Saltbush          

Speckled Alder      

Speedwell          

Spiderflower          

Spiderwort          

Spiked Muhly      

Spikemoss          

Spikenard          

Spikeoat          

Spikerush          

Spindletree          

Spinulose Woodfern          

Spiny Milkvetch          

Spiny Naiad          

Spiny Phlox          

Spiny Plumeless Thistle          

Spiny Sowthistle          

Spinystar          

Spiral Ditchgrass          

Spiral Pondweed          

Spirea          

Splitlip Hempnettle          

Spotted Fritillary          

Spotted Geranium          

Spotted Joe Pye Weed          

Spotted Knapweed          

Spotted Ladysthumb      

Spotted Sandmat          

Spotted Water Hemlock          

Sprangletop          

Spreading Dogbane          

Spreading Fleabane          

Spreading Wallflower          

Spreading Yellowcress      

Spreadingpod Rockcress      

Springparsley          

Spurge          

Spurred Gentian