| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| SIRH2 | Sidalcea rhizomata Jepson | Sidalcea calycosa ssp. rhizomata | Malvaceae
|
| SIRO2 | Sidalcea robusta Heller ex Roush | Butte County checkerbloom | Malvaceae
|
| SISEQ | Sidalcea setosa C.L. Hitchc. ssp. querceta C.L. Hitchc. | Sidalcea oregana ssp. spicata | Malvaceae
|
| SISE | Sidalcea setosa C.L. Hitchc. | Sidalcea oregana ssp. spicata | Malvaceae
|
| SISPT | Sidalcea spicata (Regel) Greene var. tonsa M.E. Peck | Sidalcea oregana ssp. spicata | Malvaceae
|
| SISPV | Sidalcea spicata (Regel) Greene var. valida (Greene) Wiggins | Sidalcea oregana ssp. valida | Malvaceae
|
| SISP5 | Sidalcea spicata (Regel) Greene | Sidalcea oregana ssp. spicata | Malvaceae
|
| SIST3 | Sidalcea stipularis J.T. Howell & True | Scadden Flat checkerbloom | Malvaceae
|
| SIVA3 | Sidalcea valida Greene | Sidalcea oregana ssp. valida | Malvaceae
|
| SIVI3 | Sidalcea virgata T.J. Howell | Sidalcea malviflora ssp. virgata | Malvaceae
|
| SIDAL | Sidalcea Gray | checkerbloom | Malvaceae
|
| SIAC5 | Sidastrum acuminatum (DC.) Fryxell | Sidastrum multiflorum | Malvaceae
|
| SIMU4 | Sidastrum multiflorum (Jacq.) Fryxell | manyflower sandmallow | Malvaceae
|
| SIPA5 | Sidastrum paniculatum (L.) Fryxell | panicled sandmallow | Malvaceae
|
| SIDAS | Sidastrum E.G. Baker | sandmallow | Malvaceae
|
| SIAN6 | Sideranthus annuus Rydb. | Rayjacksonia annua | Asteraceae
|
| SIAU3 | Sideranthus aureus (Gray) Small | Rayjacksonia aurea | Asteraceae
|
| SIAU5 | Sideranthus australis (Greene) Rydb. | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| SICO10 | Sideranthus cotula Small | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| SIGL7 | Sideranthus glaberrimus Rydb. | Machaeranthera pinnatifida ssp. pinnatifida var. glaberrima | Asteraceae
|
| SIGO | Sideranthus gooddingii A. Nels. | Machaeranthera pinnatifida ssp. gooddingii var. gooddingii | Asteraceae
|
| SIGR9 | Sideranthus gracilis (Nutt.) A. Nels. | Machaeranthera gracilis | Asteraceae
|
| SIGR12 | Sideranthus grindelioides (Nutt.) Britt. | Machaeranthera grindelioides var. grindelioides | Asteraceae
|
| SILA12 | Sideranthus laevis Woot. & Standl. | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| SIMA9 | Sideranthus machaerantherus Small | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| SIME3 | Sideranthus megacephalus (Nash) Small | Rayjacksonia phyllocephala | Asteraceae
|
| SIPU6 | Sideranthus puberulus Rydb. | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| SISPG | Sideranthus spinulosus (Pursh) Sweet ex Rydb. var. glaberrimus (Rydb.) A. Nels. | Machaeranthera pinnatifida ssp. pinnatifida var. glaberrima | Asteraceae
|
| SISP4 | Sideranthus spinulosus (Pursh) Sweet ex Rydb. | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| SITU3 | Sideranthus turbinellus Rydb. | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| SIWO | Sideranthus wootonii (Greene) Standl. | Machaeranthera pinnatifida ssp. pinnatifida var. pinnatifida | Asteraceae
|
| SILA8 | Sideritis lanata L. | hairy ironwort | Lamiaceae
|
| SIMO3 | Sideritis montana L. | mountain ironwort | Lamiaceae
|
| SIRO3 | Sideritis romana L. | simplebeak ironwort | Lamiaceae
|
| SIDER | Sideritis L. | ironwort | Lamiaceae
|
| SIAL13 | Sideroxylon alachuense L.C. Anders. | | Sapotaceae
|
| SICE2 | Sideroxylon celastrinum (Kunth) T.D. Pennington | saffron plum | Sapotaceae
|
| SICU7 | Sideroxylon cubense (Griseb.) T.D. Pennington | espejuelo | Sapotaceae
|
| SIFO | Sideroxylon foetidissimum Jacq. | false mastic | Sapotaceae
|
| SILAA4 | Sideroxylon lanuginosum Michx. ssp. albicans (Sarg.) Kartesz & Gandhi | gum bully | Sapotaceae
|
| SILAL3 | Sideroxylon lanuginosum Michx. ssp. lanuginosum | gum bully | Sapotaceae
|
| SILAO | Sideroxylon lanuginosum Michx. ssp. oblongifolium (Nutt.) T.D. Pennington | gum bully | Sapotaceae
|
| SILAR2 | Sideroxylon lanuginosum Michx. ssp. rigidum (Gray) T.D. Pennington | gum bully | Sapotaceae
|
| SILA20 | Sideroxylon lanuginosum Michx. | gum bully | Sapotaceae
|
| SILY | Sideroxylon lycioides L. | buckthorn bully | Sapotaceae
|
| SIOB | Sideroxylon obovatum Lam. | breakbill | Sapotaceae
|
| SIPO3 | Sideroxylon portoricense Urban | Puerto Rico bully | Sapotaceae
|
| SIREA2 | Sideroxylon reclinatum Michx. ssp. austrofloridense (Whetstone) Kartesz & Gandhi | Florida bully | Sapotaceae
|
| SIRER2 | Sideroxylon reclinatum Michx. ssp. reclinatum | Florida bully | Sapotaceae
|
| SIRER3 | Sideroxylon reclinatum Michx. ssp. rufotomentosum (Small) Kartesz & Gandhi | Florida bully | Sapotaceae
|
| SIRE8 | Sideroxylon reclinatum Michx. | Florida bully | Sapotaceae
|
| SIRU7 | Sideroxylon rufohirtum Herring & Judd | Sideroxylon reclinatum ssp. rufotomentosum | Sapotaceae
|
| SISA6 | Sideroxylon salicifolium (L.) Lam. | white bully | Sapotaceae
|
| SITE2 | Sideroxylon tenax L. | tough bully | Sapotaceae
|
| SITH2 | Sideroxylon thornei (Cronq.) T.D. Pennington | Georgia bully | Sapotaceae
|
| SIDER2 | Sideroxylon L. | bully | Sapotaceae
|
| SISA9 | Sideroxylum sapota Jacq. | Pouteria sapota | Sapotaceae
|
| SIHI8 | Sidopsis hispida (Pursh) Rydb. | Malvastrum hispidum | Malvaceae
|
| SIDE2 | Sieglingia decumbens (L.) Bernh. | Danthonia decumbens | Poaceae
|
| SIER2 | Siella erecta (Huds.) M. Pimen. | Berula erecta | Apiaceae
|
| SICA15 | Sieversia campanulata (Greene) Rydb. | Geum triflorum var. campanulatum | Rosaceae
|
| SICA16 | Sieversia canescens (Greene) Rydb. | Geum triflorum var. canescens | Rosaceae
|
| SICI3 | Sieversia ciliata (Pursh) G. Don | Geum triflorum var. ciliatum | Rosaceae
|
| SIGR13 | Sieversia gracilipes (Piper) Greene | Geum rossii var. turbinatum | Rosaceae
|
| SIMA12 | Sieversia �macrantha Kearney | Geum macranthum | Rosaceae
|
| SIPE6 | Sieversia peckii (Pursh) Rydb. | Geum peckii | Rosaceae
|
| SIPE7 | Sieversia pentapetala (L.) Greene | Geum pentapetalum | Rosaceae
|
| SIRA4 | Sieversia radiata (Michx.) Greene | Geum radiatum | Rosaceae
|
| SITR5 | Sieversia triflora (Pursh) R. Br. | Geum triflorum var. triflorum | Rosaceae
|
| SILA15 | Sigesbeckia laciniata Poir. | Verbesina virginica var. laciniata | Asteraceae
|
| SIOR2 | Sigesbeckia orientalis L. | common St. Paul's wort | Asteraceae
|
| SIGES | Sigesbeckia L. | St. Paul's wort | Asteraceae
|
| SICA20 | Sigridea californica (Tuck.) Tehler | | Roccellaceae
|
| SIGRI | Sigridea Tehler | sigridea | Roccellaceae
|
| SIACA | Silene acaulis (L.) Jacq. ssp. arctica A.& D. L�ve | Silene acaulis var. exscapa | Caryophyllaceae
|
| SIACS | Silene acaulis (L.) Jacq. ssp. subacaulescens (F.N. Williams) Hult�n | Silene acaulis var. subacaulescens | Caryophyllaceae
|
| SIACE | Silene acaulis (L.) Jacq. var. exscapa (All.) DC. | moss campion | Caryophyllaceae
|
| SIACS2 | Silene acaulis (L.) Jacq. var. subacaulescens (F.N. Williams) Fern. & St. John | moss campion | Caryophyllaceae
|
| SIAC | Silene acaulis (L.) Jacq. | moss campion | Caryophyllaceae
|
| SIAL12 | Silene alba (P. Mill.) Krause | Silene latifolia ssp. alba | Caryophyllaceae
|
| SIAL4 | Silene alexandri Hbd. | Kamalo Gulch catchfly | Caryophyllaceae
|
| SIAN8 | Silene andersonii Clokey | Silene verecunda ssp. andersonii | Caryophyllaceae
|
| SIAN7 | Silene anglica L. | Silene gallica | Caryophyllaceae
|
| SIANC | Silene antirrhina L. var. confinis Fern. | Silene antirrhina | Caryophyllaceae
|
| SIAND | Silene antirrhina L. var. depauperata Rydb. | Silene antirrhina | Caryophyllaceae
|
| SIAND2 | Silene antirrhina L. var. divaricata B.L. Robins. | Silene antirrhina | Caryophyllaceae
|
| SIANL | Silene antirrhina L. var. laevigata Engelm. & Gray | Silene antirrhina | Caryophyllaceae
|
| SIANS | Silene antirrhina L. var. subglaber Engelm. & Gray | Silene antirrhina | Caryophyllaceae
|
| SIANV | Silene antirrhina L. var. vaccarifolia Rydb. | Silene antirrhina | Caryophyllaceae
|
| SIAN2 | Silene antirrhina L. | sleepy silene | Caryophyllaceae
|
| SIAP | Silene aperta Greene | naked catchfly | Caryophyllaceae
|
| SIAR | Silene armeria L. | sweet William silene | Caryophyllaceae
|
| SIAT2 | Silene attenuata (Farr) Bocquet | Silene uralensis ssp. attenuata | Caryophyllaceae
|
| SIBA | Silene baldwinii Nutt. | Silene polypetala | Caryophyllaceae
|
| SIBEB | Silene bernardina S. Wats. ssp. bernardina | Palmer's catchfly | Caryophyllaceae
|
| SIBER | Silene bernardina S. Wats. ssp. maguirei Bocquet var. rigidula (B.L. Robins.) Tiehm | Palmer's catchfly | Caryophyllaceae
|
| SIBES | Silene bernardina S. Wats. ssp. maguirei Bocquet var. sierrae (C.L. Hitchc. & Maguire) Bocquet | Palmer's catchfly | Caryophyllaceae
|
| SIBEM | Silene bernardina S. Wats. ssp. maguirei Bocquet | Palmer's catchfly | Caryophyllaceae
|
| SIBE4 | Silene bernardina S. Wats. | Palmer's catchfly | Caryophyllaceae
|
| SIBR | Silene bridgesii Rohrb. | Bridges' catchfly | Caryophyllaceae
|
| SICA4 | Silene californica Dur. | Indian pink | Caryophyllaceae
|