Sorghum bicolor [Sorghum]
Sorghum sudanense [Sudan Grass]
Sour Orange Tree [Citrus aurantium]
Soybean [Glycine max]
Spartina alterniflora [Smooth Cordgrass]
Spartina anglica [Common Cordgrass]
Spartina patens [Saltmeadow Cordgrass]
Spathiphyllum [Peace Lily]
Spergula arvensis [Corn Spurrey]
Sphagnum, Magellan's [Sphagnum magellanicum]
Sphagnum, Papillose [Sphagnum papillosum]
Sphagnum, Recurved [Sphagnum recurvum]
Sphagnum, Toothed [Sphagnum cuspidatum]
Sphagnum cuspidatum [Toothed Sphagnum]
Sphagnum magellanicum [Magellan's Sphagnum]
Sphagnum papillosum [Papillose Sphagnum]
Sphagnum recurvum [Recurved Sphagnum]
Spider Lily [Hymenocallis littoralis]
Spinach [Spinacia oleracea]
Spinacia oleracea [Spinach]
Sporobolus pyramidalis [Whorled Dropseed]
Spring Vetch [Vicia lathyroides]
Spruce [Picea koraiensis]
Spruce, Black [Picea mariana]
Spruce, Norway [Picea abies]
Spruce, Red [Picea rubens]
Spruce, Sitka [Picea sitchensis]
Spruce, White [Picea glauca]
Spurrey, Corn [Spergula arvensis]
Squash, Summer [Cucurbita pepo]
St. John's Wort [Hypericum perforatum]
Stalkgrass, Broad [Pharus latifolius]
Stipa thurberiana [Thurber Needlegrass]
Strawberry, Hybrid [Fragaria x ananassa]
Striga hermonthica [Purple Witchweed]
Stylosanthes scabra [Pencilflower]
Subterranean Clover [Trifolium subterraneum]
Sugarcane [Saccharum officinarum]
Sugargum [Eucalyptus cladocalyx]
Sunflower [Helianthus annus]
Sunn Hemp [Crotalaria juncea]
Sweet Vernal Grass [Anthoxanthum odoratum]
Sweetgum [Liquidambar styraciflua]
Switchgrass [Panicum virgatum]
Swordfern, Boston [Nephrolepis exaltata]
Sycamore [Acer pseudoplatanus]
Symphiocarpos orbiculatus [Buck Brush]