| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| SOSPJ | Solidago speciosa Nutt. var. jejunifolia (Steele) Cronq. | showy goldenrod | Asteraceae
|
| SOSPP | Solidago speciosa Nutt. var. pallida Porter | showy goldenrod | Asteraceae
|
| SOSPR | Solidago speciosa Nutt. var. rigidiuscula Torr. & Gray | showy goldenrod | Asteraceae
|
| SOSPS4 | Solidago speciosa Nutt. var. speciosa | showy goldenrod | Asteraceae
|
| SOSP2 | Solidago speciosa Nutt. | showy goldenrod | Asteraceae
|
| SOSPC | Solidago spectabilis (D.C. Eat.) Gray var. confinis (Gray) Cronq. | Nevada goldenrod | Asteraceae
|
| SOSPS6 | Solidago spectabilis (D.C. Eat.) Gray var. spectabilis | Nevada goldenrod | Asteraceae
|
| SOSP3 | Solidago spectabilis (D.C. Eat.) Gray | Nevada goldenrod | Asteraceae
|
| SOSP4 | Solidago sphacelata Raf. | autumn goldenrod | Asteraceae
|
| SOSP6 | Solidago spithamaea M.A. Curtis | Blue Ridge goldenrod | Asteraceae
|
| SOSQ | Solidago squarrosa Nutt. | stout goldenrod | Asteraceae
|
| SOST | Solidago stricta Ait. | wand goldenrod | Asteraceae
|
| SOST2 | Solidago strigosa Small | Solidago patula var. strictula | Asteraceae
|
| SOSU5 | Solidago suaveolens Schoepf | Solidago odora var. odora | Asteraceae
|
| SOTA2 | Solidago tarda Mackenzie | Solidago arguta var. arguta | Asteraceae
|
| SOTEP | Solidago tenuifolia Pursh var. pycnocephala Fern. | Euthamia tenuifolia var. pycnocephala | Asteraceae
|
| SOTE5 | Solidago tenuifolia Pursh | Euthamia tenuifolia var. tenuifolia | Asteraceae
|
| SOTE6 | Solidago tenuissima Woot. & Standl. | Solidago missouriensis var. tenuissima | Asteraceae
|
| SOTE7 | Solidago texensis Friesner | Euthamia gymnospermoides | Asteraceae
|
| SOTO2 | Solidago tortifolia Ell. | twistleaf goldenrod | Asteraceae
|
| SOTR3 | Solidago trinervata Greene | Solidago velutina | Asteraceae
|
| SOULJ | Solidago uliginosa Nutt. var. jejunifolia (Steele) Boivin | Solidago speciosa var. jejunifolia | Asteraceae
|
| SOULL | Solidago uliginosa Nutt. var. levipes (Fern.) Fern. | bog goldenrod | Asteraceae
|
| SOULL2 | Solidago uliginosa Nutt. var. linoides (Torr. & Gray) Fern. | bog goldenrod | Asteraceae
|
| SOULN | Solidago uliginosa Nutt. var. neglecta (Torr. & Gray) Fern. | Solidago uliginosa var. uliginosa | Asteraceae
|
| SOULP | Solidago uliginosa Nutt. var. peracuta (Fern.) Friesner | Solidago uliginosa var. linoides | Asteraceae
|
| SOULT | Solidago uliginosa Nutt. var. terrae-novae (Torr. & Gray) Fern. | bog goldenrod | Asteraceae
|
| SOULU | Solidago uliginosa Nutt. var. uliginosa | bog goldenrod | Asteraceae
|
| SOUL | Solidago uliginosa Nutt. | bog goldenrod | Asteraceae
|
| SOUL4 | Solidago �ulmicaesia Friesner | | Asteraceae
|
| SOULM | Solidago ulmifolia Muhl. ex Willd. var. microphylla Gray | elmleaf goldenrod | Asteraceae
|
| SOULP2 | Solidago ulmifolia Muhl. ex Willd. var. palmeri Cronq. | Palmer's goldenrod | Asteraceae
|
| SOULU2 | Solidago ulmifolia Muhl. ex Willd. var. ulmifolia | elmleaf goldenrod | Asteraceae
|
| SOUL2 | Solidago ulmifolia Muhl. ex Willd. | elmleaf goldenrod | Asteraceae
|
| SOUNL | Solidago uniligulata (DC.) Porter var. levipes Fern. | Solidago uliginosa var. levipes | Asteraceae
|
| SOUN | Solidago uniligulata (DC.) Porter | Solidago uliginosa var. uliginosa | Asteraceae
|
| SOVEN | Solidago velutina DC. var. nevadensis (Gray) C.& J. Taylor | Solidago velutina | Asteraceae
|
| SOVE6 | Solidago velutina DC. | threenerve goldenrod | Asteraceae
|
| SOVE2 | Solidago verna M.A. Curtis | springflowering goldenrod | Asteraceae
|
| SOVIA | Solidago virgauera L. var. arctica DC. | Solidago multiradiata var. arctica | Asteraceae
|
| SOWA2 | Solidago wardii Britt. | Solidago petiolaris var. angusta | Asteraceae
|
| SOWRA | Solidago wrightii Gray var. adenophora Blake | Wright's goldenrod | Asteraceae
|
| SOWRW | Solidago wrightii Gray var. wrightii | Wright's goldenrod | Asteraceae
|
| SOWR | Solidago wrightii Gray | Wright's goldenrod | Asteraceae
|
| SOYA | Solidago yadkinensis (Porter) Small | Solidago arguta var. caroliniana | Asteraceae
|
| SOLID | Solidago L. | goldenrod | Asteraceae
|
| SOAN7 | Soliva anthemifolia (Juss.) R. Br. ex Less. | Gymnostyles anthemifolia | Asteraceae
|
| SODA | Soliva daucifolia Nutt. | Soliva sessilis | Asteraceae
|
| SOMU2 | Soliva mutisii Kunth | Mutis' burrweed | Asteraceae
|
| SONA3 | Soliva nasturtiifolia auct. non (Juss.) DC. | Gymnostyles stolonifera | Asteraceae
|
| SOPT | Soliva pterosperma (Juss.) Less. | Soliva sessilis | Asteraceae
|
| SOSE2 | Soliva sessilis Ruiz & Pav�n | field burrweed | Asteraceae
|
| SOST6 | Soliva stolonifera (Brot.) Loud. | Gymnostyles stolonifera | Asteraceae
|
| SOLIV | Soliva Ruiz & Pav�n | burrweed | Asteraceae
|
| SOFU2 | Sollya fusiformis (Labill.) Briq. | Sollya heterophylla | Pittosporaceae
|
| SOHE2 | Sollya heterophylla Lindl. | bluebell creeper | Pittosporaceae
|
| SOLLY | Sollya Lindl. | sollya | Pittosporaceae
|
| SOBI4 | Solmsiella biseriata (Aust.) Steere | Erpodium biseriatum | Erpodiaceae
|
| SOKU | Solmsiella kurzii Steere | Erpodium biseriatum | Erpodiaceae
|
| SOBI60 | Solorina bispora Nyl. | chocolate chip lichen | Peltigeraceae
|
| SOCR60 | Solorina crocea (L.) Ach. | chocolate chip lichen | Peltigeraceae
|
| SOOC5 | Solorina octospora (Arnold) Arnold | chocolate chip lichen | Peltigeraceae
|
| SOSA60 | Solorina saccata (L.) Ach. | chocolate chip lichen | Peltigeraceae
|
| SOSP60 | Solorina spongiosa (Ach.) Anzi | chocolate chip lichen | Peltigeraceae
|
| SOLOR2 | Solorina Ach. | chocolate chip lichen | Peltigeraceae
|
| SODE7 | Solorinaria despreauxii (Mont.) Fink | Heppia lutosa | Heppiaceae
|
| SOAS3 | Solorinella asteriscus Anzi | | Solorinellaceae
|
| SOLOR3 | Solorinella Anzi | solorinella | Solorinellaceae
|
| SOARA2 | Sonchus arvensis L. ssp. arvensis | field sowthistle | Asteraceae
|
| SOARU | Sonchus arvensis L. ssp. uliginosus (Bieb.) Nyman | moist sowthistle | Asteraceae
|
| SOARG | Sonchus arvensis L. var. glabrescens Guenth., Grab. & Wimmer | Sonchus arvensis ssp. uliginosus | Asteraceae
|
| SOARS2 | Sonchus arvensis L. var. shumovichii Boivin | Sonchus arvensis ssp. arvensis | Asteraceae
|
| SOAR2 | Sonchus arvensis L. | field sowthistle | Asteraceae
|
| SOAS | Sonchus asper (L.) Hill | spiny sowthistle | Asteraceae
|
| SOOL | Sonchus oleraceus L. | common sowthistle | Asteraceae
|
| SOPA10 | Sonchus palustris L. | marsh sowthistle | Asteraceae
|
| SOTA | Sonchus tataricus L. p.p. | Lactuca tatarica var. pulchella | Asteraceae
|
| SOTE3 | Sonchus tenerrimus L. | slender sowthistle | Asteraceae
|
| SOUL5 | Sonchus uliginosus Bieb. | Sonchus arvensis ssp. uliginosus | Asteraceae
|
| SONCH | Sonchus L. | sowthistle | Asteraceae
|
| SOAL10 | Sonneratia alba J.E. Smith | | Sonneratiaceae
|
| SONNE | Sonneratia L. f. | | Sonneratiaceae
|
| SOANO2 | Sophia andrenarium Cockerell var. osmiarum Cockerell | Descurainia pinnata ssp. halictorum | Brassicaceae
|
| SOAN6 | Sophia andrenarium Cockerell | Descurainia pinnata ssp. halictorum | Brassicaceae
|
| SOBR2 | Sophia brachycarpa (Richards.) Rydb. | Descurainia pinnata ssp. brachycarpa | Brassicaceae
|
| SOFI2 | Sophia filipes (Gray) Heller | Descurainia pinnata ssp. filipes | Brassicaceae
|
| SOGL5 | Sophia glabra Woot. & Standl. | Descurainia pinnata ssp. glabra | Brassicaceae
|
| SOHA5 | Sophia halictorum Cockerell | Descurainia pinnata ssp. halictorum | Brassicaceae
|
| SOHA6 | Sophia hartwegiana (Fourn.) Greene | Descurainia incana ssp. procera | Brassicaceae
|
| SOIN3 | Sophia incisa (Engelm.) Greene | Descurainia incana ssp. incisa | Brassicaceae
|
| SOIN4 | Sophia intermedia Rydb. | Descurainia pinnata ssp. intermedia | Brassicaceae
|
| SOMI4 | Sophia millefolia Rydb. ex Britt. | Descurainia pinnata ssp. pinnata | Brassicaceae
|
| SOMU4 | Sophia multifida (Pursh) O.E. Schulz | Descurainia pinnata ssp. pinnata | Brassicaceae
|
| SONE6 | Sophia nelsonii Rydb. | Descurainia pinnata ssp. nelsonii | Brassicaceae
|
| SOOC2 | Sophia ochroleuca Woot. | Descurainia pinnata ssp. ochroleuca | Brassicaceae
|
| SOPA6 | Sophia paradisa A. Nels. & Kennedy | Descurainia paradisa ssp. paradisa | Brassicaceae
|
| SOPI6 | Sophia pinnata (Walt.) T.J. Howell | Descurainia pinnata ssp. pinnata | Brassicaceae
|
| SOPR2 | Sophia procera Greene | Descurainia incana ssp. procera | Brassicaceae
|
| SORI5 | Sophia richardsonii (O.E. Schulz) Rydb. | Descurainia incana ssp. incana | Brassicaceae
|
| SOSO7 | Sophia sophia (L.) Britt. | Descurainia sophia | Brassicaceae
|
| SOVI4 | Sophia viscosa Rydb. | Descurainia incana ssp. viscosa | Brassicaceae
|