| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| SPCOM | Sporobolus compositus (Poir.) Merr. var. macer (Trin.) Kartesz & Gandhi | composite dropseed | Poaceae
|
| SPCO16 | Sporobolus compositus (Poir.) Merr. | composite dropseed | Poaceae
|
| SPCO11 | Sporobolus confusus auct. non (Fourn.) Vasey | Muhlenbergia minutissima | Poaceae
|
| SPCO4 | Sporobolus contractus A.S. Hitchc. | spike dropseed | Poaceae
|
| SPCO17 | Sporobolus coromandelianus (Retz.) Kunth | Madagascar dropseed | Poaceae
|
| SPCRF | Sporobolus cryptandrus (Torr.) Gray ssp. fuscicola (Hook.) E.K. Jones & Fassett | Sporobolus cryptandrus | Poaceae
|
| SPCRF2 | Sporobolus cryptandrus (Torr.) Gray var. fuscicola (Hook.) Pohl | Sporobolus cryptandrus | Poaceae
|
| SPCRO | Sporobolus cryptandrus (Torr.) Gray var. occidentalis E.K. Jones & Fassett | Sporobolus cryptandrus | Poaceae
|
| SPCRS | Sporobolus cryptandrus (Torr.) Gray var. strictus Scribn. | Sporobolus contractus | Poaceae
|
| SPCR | Sporobolus cryptandrus (Torr.) Gray | sand dropseed | Poaceae
|
| SPCU2 | Sporobolus cubensis A.S. Hitchc. | Cuban dropseed | Poaceae
|
| SPCU | Sporobolus curtissii (Vasey ex Beal) Small ex Scribn. | Curtis' dropseed | Poaceae
|
| SPDI4 | Sporobolus diander (Retz.) Beauv. | tussock dropseed | Poaceae
|
| SPDO2 | Sporobolus domingensis (Trin.) Kunth | coral dropseed | Poaceae
|
| SPDR | Sporobolus drummondii (Trin.) Vasey | Sporobolus compositus var. drummondii | Poaceae
|
| SPEL | Sporobolus elongatus R. Br. | elongate dropseed | Poaceae
|
| SPFI6 | Sporobolus fimbriatus (Trin.) Nees | fringed dropseed | Poaceae
|
| SPFL2 | Sporobolus flexuosus (Thurb. ex Vasey) Rydb. | mesa dropseed | Poaceae
|
| SPFL3 | Sporobolus floridanus Chapman | Florida dropseed | Poaceae
|
| SPGI | Sporobolus giganteus Nash | giant dropseed | Poaceae
|
| SPGR4 | Sporobolus gracilis (Trin.) Merr. | Sporobolus junceus | Poaceae
|
| SPHE | Sporobolus heterolepis (Gray) Gray | prairie dropseed | Poaceae
|
| SPINC3 | Sporobolus indicus (L.) R. Br. var. capensis Engelm. | rat-tail grass | Poaceae
|
| SPINI2 | Sporobolus indicus (L.) R. Br. var. indicus | smut grass | Poaceae
|
| SPINP2 | Sporobolus indicus (L.) R. Br. var. pyramidalis (Beauv.) Veldkamp | West Indian dropseed | Poaceae
|
| SPIN4 | Sporobolus indicus (L.) R. Br. | smut grass | Poaceae
|
| SPIN5 | Sporobolus interruptus Vasey | black dropseed | Poaceae
|
| SPJA2 | Sporobolus jacquemontii Kunth | Sporobolus indicus var. pyramidalis | Poaceae
|
| SPJU | Sporobolus junceus (Beauv.) Kunth | pineywoods dropseed | Poaceae
|
| SPLO4 | Sporobolus longifolius (Torr.) Wood | Sporobolus clandestinus | Poaceae
|
| SPMA8 | Sporobolus macer (Trin.) A.S. Hitchc. | Sporobolus compositus var. macer | Poaceae
|
| SPMI10 | Sporobolus microspermus (Lag.) A. Hitchcock | dropseed | Poaceae
|
| SPMU4 | Sporobolus muralis (Raddi) A.S. Hitchc. & Chase | Sporobolus tenuissimus | Poaceae
|
| SPNE | Sporobolus nealleyi Vasey | gyp dropseed | Poaceae
|
| SPNEO | Sporobolus neglectus Nash var. ozarkanus (Fern.) Steyermark & Kucera | Sporobolus vaginiflorus var. ozarkanus | Poaceae
|
| SPNE2 | Sporobolus neglectus Nash | puffsheath dropseed | Poaceae
|
| SPOZ | Sporobolus ozarkanus Fern. | Sporobolus vaginiflorus var. ozarkanus | Poaceae
|
| SPPA6 | Sporobolus patens auct. non Swallen | Sporobolus coromandelianus | Poaceae
|
| SPPI2 | Sporobolus piliferus (Trin.) Kunth | Barundi dropseed | Poaceae
|
| SPPI | Sporobolus pilosus Vasey | Sporobolus compositus var. drummondii | Poaceae
|
| SPPO2 | Sporobolus poiretii (Roemer & J.A. Schultes) A.S. Hitchc. | Sporobolus indicus var. indicus | Poaceae
|
| SPPU2 | Sporobolus pulvinatus Swallen | Sporobolus coromandelianus | Poaceae
|
| SPPU3 | Sporobolus purpurascens (Sw.) Hamilton | purple dropseed | Poaceae
|
| SPPY2 | Sporobolus pyramidatus (Lam.) A.S. Hitchc. | Sporobolus coromandelianus | Poaceae
|
| SPRA3 | Sporobolus ramulosus (Kunth) Kunth | Muhlenbergia ramulosa | Poaceae
|
| SPSI2 | Sporobolus silveanus Swallen | Silveus' dropseed | Poaceae
|
| SPTE3 | Sporobolus tenuissimus (Mart. ex Schrank) Kuntze | tropical dropseed | Poaceae
|
| SPTE4 | Sporobolus teretifolius Harper | wireleaf dropseed | Poaceae
|
| SPTE5 | Sporobolus texanus Vasey | Texas dropseed | Poaceae
|
| SPTH | Sporobolus tharpii A.S. Hitchc. | Tharp's dropseed | Poaceae
|
| SPTO7 | Sporobolus torreyanus (J.A. Schultes) Nash | Muhlenbergia torreyana | Poaceae
|
| SPUN2 | Sporobolus uniflorus (Muhl.) Scribn. & Merr. | Muhlenbergia uniflora | Poaceae
|
| SPVAI | Sporobolus vaginiflorus (Torr. ex Gray) Wood var. inaequalis Fern. | Sporobolus vaginiflorus var. vaginiflorus | Poaceae
|
| SPVAN | Sporobolus vaginiflorus (Torr. ex Gray) Wood var. neglectus (Nash) Scribn. | Sporobolus neglectus | Poaceae
|
| SPVAO | Sporobolus vaginiflorus (Torr. ex Gray) Wood var. ozarkanus (Fern.) Shinners | Ozark dropseed | Poaceae
|
| SPVAV2 | Sporobolus vaginiflorus (Torr. ex Gray) Wood var. vaginiflorus | poverty dropseed | Poaceae
|
| SPVA | Sporobolus vaginiflorus (Torr. ex Gray) Wood | poverty dropseed | Poaceae
|
| SPVI3 | Sporobolus virginicus (L.) Kunth | seashore dropseed | Poaceae
|
| SPWR2 | Sporobolus wrightii Munro ex Scribn. | big sacaton | Poaceae
|
| SPORO | Sporobolus R. Br. | dropseed | Poaceae
|
| SPPH | Sporopodium phyllocharis (Mont.) A. Massal. | | Ectolechiaceae
|
| SPORO2 | Sporopodium Mont. | sporopodium | Ectolechiaceae
|
| SPMO3 | Spraguea monosperma (Greene) Rydb. | Cistanthe monosperma | Portulacaceae
|
| SPUMC | Spraguea umbellata Torr. var. caudicifera Gray | Cistanthe umbellata var. caudicifera | Portulacaceae
|
| SPUM | Spraguea umbellata Torr. | Cistanthe umbellata var. umbellata | Portulacaceae
|
| SPFO4 | Sprekelia formisissima (L.) Herb. | Jacobean Lily | Liliaceae
|
| SPREK | Sprekelia Heist. | Jacobean Lily | Liliaceae
|
| SQCA | Squamarina cartilaginea (With.) P. James | rim lichen | Bacidiaceae
|
| SQCR | Squamarina crassa (Hudson) Poelt | Squamarina cartilaginea | Bacidiaceae
|
| SQDE | Squamarina degelii Frey & Poelt | Degel's rim lichen | Bacidiaceae
|
| SQLE | Squamarina lentigera (Weber) Poelt | rim lichen | Bacidiaceae
|
| SQUAM | Squamarina Poelt | rim lichen | Bacidiaceae
|
| STAN11 | Stachydeoma angulata Tharp | Rhododon angulatus | Lamiaceae
|
| STGR6 | Stachydeoma graveolens (Chapman ex Gray) Small | mock pennyroyal | Lamiaceae
|
| STACH3 | Stachydeoma Small | mock pennyroyal | Lamiaceae
|
| STAF2 | Stachys affinis Bunge | artichoke betony | Lamiaceae
|
| STAG | Stachys agraria auct. non Cham. & Schlecht. | Stachys crenata | Lamiaceae
|
| STAJR | Stachys ajugoides Benth. var. rigida Jepson & Hoover | Stachys rigida var. rigida | Lamiaceae
|
| STAJ | Stachys ajugoides Benth. | bugle hedgenettle | Lamiaceae
|
| STAL | Stachys albens Gray | whitestem hedgenettle | Lamiaceae
|
| STAM8 | Stachys ambigua (Gray) Britt. | Stachys aspera | Lamiaceae
|
| STAN | Stachys annua (L.) L. | annual hedgenettle | Lamiaceae
|
| STAR5 | Stachys arenicola Britt. | Stachys pilosa var. arenicola | Lamiaceae
|
| STAR | Stachys arvensis (L.) L. | staggerweed | Lamiaceae
|
| STAS | Stachys aspera Michx. | hyssopleaf hedgenettle | Lamiaceae
|
| STAS3 | Stachys asperrima Rydb. | Stachys pilosa var. pilosa | Lamiaceae
|
| STAT2 | Stachys atlantica Britt. | Stachys hyssopifolia | Lamiaceae
|
| STBE6 | Stachys bergii G. Mulligan & D. Munro | His Excellency's supreme reflection | Lamiaceae
|
| STBI | Stachys bigelovii Gray | rock hedgenettle | Lamiaceae
|
| STBO4 | Stachys borealis Rydb. | Stachys pilosa var. pilosa | Lamiaceae
|
| STBU | Stachys bullata Benth. | California hedgenettle | Lamiaceae
|
| STBY | Stachys byzantina K. Koch ex Scheele | woolly hedgenettle | Lamiaceae
|
| STCHC2 | Stachys chamissonis Benth. var. chamissonis | coastal hedgenettle | Lamiaceae
|
| STCHC3 | Stachys chamissonis Benth. var. cooleyae (Heller) G. Mulligan & D. Munro | coastal hedgenettle | Lamiaceae
|
| STCH | Stachys chamissonis Benth. | coastal hedgenettle | Lamiaceae
|
| STCI7 | Stachys ciliata Dougl. ex Benth. | Stachys mexicana | Lamiaceae
|
| STCI2 | Stachys ciliata Epling | Stachys chamissonis var. cooleyae | Lamiaceae
|
| STCL | Stachys clingmanii Small | Clingman's hedgenettle | Lamiaceae
|
| STCO | Stachys coccinea Ortega | scarlet hedgenettle | Lamiaceae
|
| STCO14 | Stachys cooleyae Heller | Stachys chamissonis var. cooleyae | Lamiaceae
|
| STCO9 | Stachys cordata Riddell | Stachys nuttallii | Lamiaceae
|