Soapwort _Saponaria_ 52 Solomonplume _Smilacina_ 30 Solomonseal _Polygonatum_ 29 Sophora _Sophora_ 34 Sorghum _Sorghum_ 25 Sorrel _Rumex_ 51 Sowthistle _Sonohus_ 53 Soybean _Glycine_ 31 Spanishneedles _Bidens bipinnata_ 37 Speedwell _Veronica_ 55 Spermolepis _Spermolepis_ 53 Spiderflower _Cleome_ 39 Spiderwort _Tradescantia_ 30 Spikesedge _Eleocharis_ 27 Spleenwort _Aspleninum_ 28 Sprangletop _Leptochloa_ 22 Springbeauty _Claytonia_ 39 Spurge _Euphorbia_ 42 Squirreltail _Sitanion_ 25 St. augustinegrass _Stenotaphrum_ 26 St. johnswort _Hypericum_ 45 Stargrass _Cynodon plectostachyum_ 20 Stenosiphon _Stenosiphon_ 54 Stickseed _Hackelia_; _Lappula_ 44, 46 Stillingia _Stillingia_ 54 Stinkgrass _Eragrostis cilianensis_ 21 Stonecrop _Sedum_ 52 Strawberry _Fragaria_ 42 Sudangrass _Sorghum bicolor_ var. _sudanense_ 25 Sugarcane _Saccharum_ 25 Sulla _Hedysarum_ 32 Sumac _Rhus_ 58 Sumpweed _Iva_ 45 Sunflower _Helianthus_ 44 Sunrose _Helianthemum_ 44 Sweetclover _Melilotus_ 33 Sweetflag _Acorus_ 29 Sweetpea _Lathyrus odoratus_ 32 Sweetpotato _Ipomoea batatas_ 45 Sweetroot _Osmorhiza_ 49 Switchgrass _Panicum virgatum_ 24 Sycamore _Platanus_ 57