Sorghum bicolor [Sorghum]
Sorghum halapense [Johnsongrass]
Soybean [Glycine max]
Spanish Elm [Cordia alliodora]
Spartina alterniflora [Smooth Cordgrass
Spartina anglica [Common Cordgrass
Spartina patens [Saltmeadow Cordgrass]
Spatiphylum cannifolium [a 75-cm-tall herb]
Spergularia maritima [Media Sandspurry]
Sphagnum [Sphagnum fuscum]
Sphagnum fuscum [Sphagnum]
Spinach [Spinacia oleracea]
Spinacia oleracea [Spinach]
Spruce, Black [Picea mariana]
Spruce, Norway [Picea abies]
Spruce, Sitka [Picea sitchensis]
Spurge, Japanese [Pachysandra terminalis]
St. John's Wort [Hypericum perforatum]
Staggerbush, Piedmont [Lyonia mariana]
Stenocereus queretaroensis [Tree Cactus]
Stiff Goldenrod [Solidago rigida]
Stinkingtoe [Hymenaea courbaril]
Stipa thurberiana [Thurber needlegrass]
Strawberry, Hybrid [Fragaria x ananassa]
Strawberry Tree [Arbutus unedo]
Sugar Maple [Acer saccharum]
Sugarcane [Saccharum officinarum]
Sugargum [Eucalyptus cladocalyx]
Sunflower [Helianthus annuus]
Sunflower, Prairie [Helainthus petiolaris]
Sweetgum [Liquidambar styraciflua]
Swietenia macrophylla [Honduras Mahogany]
Switchgrass [Panicum virgatum]
Swordfern, Boston [Nephrolepis exaltata]
Sycamore, American [Platanus occidentalis]
Symphiocarpos orbiculatus [Buch Brush]
Synechococcus [Unicellular Marine Picocyanobacterium]