| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| STNE2 | Stipa neomexicana (Thurb. ex Coult.) Scribn. | Hesperostipa neomexicana | Poaceae
|
| STNE4 | Stipa nevadensis B.L. Johnson | Achnatherum nevadense | Poaceae
|
| STOCC | Stipa occidentalis Thurb. ex S. Wats. var. californica (Merr. & Burtt-Davy ex Hall) C.L. Hitchc. | Achnatherum occidentale ssp. californicum | Poaceae
|
| STOCM | Stipa occidentalis Thurb. ex S. Wats. var. minor sensu C.L. Hitchc., non (Vasey) C.L. Hitchc. | Achnatherum nelsonii ssp. dorei | Poaceae
|
| STOCN | Stipa occidentalis Thurb. ex S. Wats. var. nelsonii (Scribn.) C.L. Hitchc. | Achnatherum nelsonii ssp. nelsonii | Poaceae
|
| STOCP | Stipa occidentalis Thurb. ex S. Wats. var. pubescens (Vasey) Maze, Taylor & MacBryde | Achnatherum occidentale ssp. pubescens | Poaceae
|
| STOC2 | Stipa occidentalis Thurb. ex S. Wats. | Achnatherum occidentale ssp. occidentale | Poaceae
|
| STPA17 | Stipa parishii Vasey | Achnatherum parishii var. parishii | Poaceae
|
| STPE10 | Stipa perplexa (Hoge & Barkworth) J. Wipff & S.D. Jones | Achnatherum perplexum | Poaceae
|
| STPI2 | Stipa pinetorum M.E. Jones | Achnatherum pinetorum | Poaceae
|
| STPO7 | Stipa porteri Rydb. | Ptilagrostis porteri | Poaceae
|
| STPR2 | Stipa pringlei (Beal) Scribn. | Piptochaetium pringlei | Poaceae
|
| STPU2 | Stipa pulchra A.S. Hitchc. | Nassella pulchra | Poaceae
|
| STRI2 | Stipa richardsonii Link | Achnatherum richardsonii | Poaceae
|
| STRO3 | Stipa robusta (Vasey) Scribn. | Achnatherum robustum | Poaceae
|
| STSC2 | Stipa scribneri Vasey | Achnatherum scribneri | Poaceae
|
| STSPC2 | Stipa spartea Trin. var. curtiseta A.S. Hitchc. | Hesperostipa curtiseta | Poaceae
|
| STSP2 | Stipa spartea Trin. | Hesperostipa spartea | Poaceae
|
| STSP3 | Stipa speciosa Trin. & Rupr. | Achnatherum speciosum | Poaceae
|
| STST2 | Stipa stillmanii Boland. | Achnatherum stillmanii | Poaceae
|
| STTE13 | Stipa tenacissima L. | esparto | Poaceae
|
| STTE4 | Stipa tenuissima Trin. | Nassella tenuissima | Poaceae
|
| STTH2 | Stipa thurberiana Piper | Achnatherum thurberianum | Poaceae
|
| STTR8 | Stipa trichotoma Nees | Nassella trichotoma | Poaceae
|
| STVA4 | Stipa vaseyi Scribn. | Achnatherum robustum | Poaceae
|
| STVI4 | Stipa viridula Trin. | Nassella viridula | Poaceae
|
| STWE | Stipa webberi (Thurb.) B.L. Johnson | Achnatherum webberi | Poaceae
|
| STWI | Stipa williamsii Scribn. | Achnatherum nelsonii ssp. nelsonii | Poaceae
|
| STIPA | Stipa L. | | Poaceae
|
| STBL5 | Stiporyzopsis bloomeri (Boland.) B.L. Johnson | Achnatherum bloomeri | Poaceae
|
| STCA13 | �Stiporyzopsis caduca (Beal) B.L. Johnson & Rogler | � Achnella caduca | Poaceae
|
| STFI3 | Stipulicida filiformis Nash | Stipulicida setacea var. setacea | Caryophyllaceae
|
| STSEL2 | Stipulicida setacea Michx. var. lacerata James | pineland scalypink | Caryophyllaceae
|
| STSES | Stipulicida setacea Michx. var. setacea | pineland scalypink | Caryophyllaceae
|
| STSE3 | Stipulicida setacea Michx. | pineland scalypink | Caryophyllaceae
|
| STIPU | Stipulicida Michx. | stipulicida | Caryophyllaceae
|
| STAL9 | Stirtonia alba (Mull. Arg.) | | Arthoniaceae
|
| STIRT | Stirtonia A. L. Sm. | stirtonia | Arthoniaceae
|
| STDE | Stizolobium deeringianum Bort | Mucuna pruriens var. utilis | Fabaceae
|
| STPR5 | Stizolobium pruriens (L.) Medik. | Mucuna pruriens var. pruriens | Fabaceae
|
| STPR4 | Stizolobium pruritum (Wight) Piper | Mucuna pruriens var. pruriens | Fabaceae
|
| STLA6 | Stokesia laevis (Hill) Greene | Stokes' aster | Asteraceae
|
| STOKE | Stokesia L'H�r. | stokesia | Asteraceae
|
| STBR7 | Stokesiella brittoniae (Grout) Robins. | Eurhynchium praelongum | Brachytheciaceae
|
| STOR5 | Stokesiella oregana (Sull.) Robins. | Eurhynchium oreganum | Brachytheciaceae
|
| STPRC | Stokesiella praelonga (Hedw.) Robins. var. californicum (Grout) Crum & Anderson | Eurhynchium praelongum | Brachytheciaceae
|
| STPRS | Stokesiella praelonga (Hedw.) Robins. var. stokesii (Turn.) Crum | Eurhynchium praelongum | Brachytheciaceae
|
| STPR7 | Stokesiella praelonga (Hedw.) Robins. | Eurhynchium praelongum | Brachytheciaceae
|
| STCO15 | Stomoisia cornuta (Michx.) Raf. | Utricularia cornuta | Lentibulariaceae
|
| STJU | Stomoisia juncea (Vahl) Barnh. | Utricularia juncea | Lentibulariaceae
|
| STVI10 | Stomoisia virgatula (Barnh.) Barnh. | Utricularia juncea | Lentibulariaceae
|
| STMI9 | Strangospora microhaema (Norman) R. Anderson | | Acarosporaceae
|
| STMO5 | Strangospora moriformis (Ach.) Stein | | Acarosporaceae
|
| STOC5 | Strangospora ochrophora (Nyl.) R. Anderson | | Acarosporaceae
|
| STPI8 | Strangospora pinicola (A. Massal.) Korber | | Acarosporaceae
|
| STRAN | Strangospora A. Massal. | strangospora | Acarosporaceae
|
| STAL8 | Stratiotes alismoides L. | Ottelia alismoides | Hydrocharitaceae
|
| STAL6 | Stratiotes aloides L. | water soldiers | Hydrocharitaceae
|
| STRAT | Stratiotes L. | water soldiers | Hydrocharitaceae
|
| STCO20 | Streblotrichum convolutum (Hedw.) P. Beauv. | Barbula convoluta var. convoluta | Pottiaceae
|
| STAN9 | Streblus anthropophagorum (Seem.) Corner | streblus | Moraceae
|
| STPE3 | Streblus pendulinus (Endl.) F. Muell. | Hawai'i roughbush | Moraceae
|
| STSA2 | Streblus sandwicensis (O. Deg.) St. John | Streblus pendulinus | Moraceae
|
| STREB | Streblus Lour. | streblus | Moraceae
|
| STRE5 | Strelitzia reginae Aiton | bird-of-paradise | Strelitziaceae
|
| STREL | Strelitzia Ait. | bird-of-paradise | Strelitziaceae
|
| STLOD | Streptanthella longirostris (S. Wats.) Rydb. var. derelicta J.T. Howell | Streptanthella longirostris | Brassicaceae
|
| STLO4 | Streptanthella longirostris (S. Wats.) Rydb. | longbeak streptanthella | Brassicaceae
|
| STREP | Streptanthella Rydb. | streptanthella | Brassicaceae
|
| STALA | Streptanthus albidus Greene ssp. albidus | Metcalf Canyon jewelflower | Brassicaceae
|
| STALP | Streptanthus albidus Greene ssp. peramoenus (Greene) Kruckeberg | most beautiful jewelflower | Brassicaceae
|
| STAL5 | Streptanthus albidus Greene | Metcalf Canyon jewelflower | Brassicaceae
|
| STAMB | Streptanthus amplexicaulis (S. Wats.) Jepson var. barbarae J.T. Howell | Caulanthus amplexicaulis var. barbarae | Brassicaceae
|
| STAM7 | Streptanthus amplexicaulis (S. Wats.) Jepson | Caulanthus amplexicaulis var. amplexicaulis | Brassicaceae
|
| STAR4 | Streptanthus arcuatus Nutt. | Arabis sparsiflora var. arcuata | Brassicaceae
|
| STARL | Streptanthus arizonicus S. Wats. var. luteus Kearney & Peebles | Streptanthus carinatus ssp. arizonicus | Brassicaceae
|
| STAR8 | Streptanthus arizonicus S. Wats. | Streptanthus carinatus ssp. arizonicus | Brassicaceae
|
| STBA2 | Streptanthus barbatus S. Wats. | Pacific jewelflower | Brassicaceae
|
| STBA3 | Streptanthus barbiger Greene | bearded jewelflower | Brassicaceae
|
| STBA4 | Streptanthus batrachopus J.L. Morrison | Mt. Tamalpais jewelflower | Brassicaceae
|
| STBE | Streptanthus bernardinus (Greene) Parish | Laguna Mountain jewelflower | Brassicaceae
|
| STBRB | Streptanthus brachiatus F.W. Hoffmann ssp. brachiatus | Socrates Mine jewelflower | Brassicaceae
|
| STBRH2 | Streptanthus brachiatus F.W. Hoffmann ssp. hoffmanii Dolan & LaPre | Socrates Mine jewelflower | Brassicaceae
|
| STBR4 | Streptanthus brachiatus F.W. Hoffmann | Socrates Mine jewelflower | Brassicaceae
|
| STBR | Streptanthus bracteatus Gray | bracted jewelflower | Brassicaceae
|
| STBR6 | Streptanthus brazoensis Buckl. | Arabis petiolaris | Brassicaceae
|
| STBRH | Streptanthus breweri Gray var. hesperidis (Jepson) Jepson | Streptanthus hesperidis | Brassicaceae
|
| STBR2 | Streptanthus breweri Gray | Brewer's jewelflower | Brassicaceae
|
| STCA34 | Streptanthus californicus (S. Wats.) Greene | Stanfordia californica | Brassicaceae
|
| STCA3 | Streptanthus callistus J.L. Morrison | Mt. Hamilton jewelflower | Brassicaceae
|
| STCAB | Streptanthus campestris S. Wats. var. bernardinus (Greene) I.M. Johnston | Streptanthus bernardinus | Brassicaceae
|
| STCA4 | Streptanthus campestris S. Wats. | southern jewelflower | Brassicaceae
|
| STCAA | Streptanthus carinatus C. Wright ex Gray ssp. arizonicus (S. Wats.) Kruckeberg, Rodman & Worthington | lyreleaf jewelflower | Brassicaceae
|
| STCAC | Streptanthus carinatus C. Wright ex Gray ssp. carinatus | lyreleaf jewelflower | Brassicaceae
|
| STCA5 | Streptanthus carinatus C. Wright ex Gray | lyreleaf jewelflower | Brassicaceae
|
| STCOC | Streptanthus cordatus Nutt. var. cordatus | heartleaf twistflower | Brassicaceae
|
| STCOD2 | Streptanthus cordatus Nutt. var. duranii Jepson | heartleaf twistflower | Brassicaceae
|
| STCOP | Streptanthus cordatus Nutt. var. piutensis J.T. Howell | heartleaf twistflower | Brassicaceae
|
| STCO6 | Streptanthus cordatus Nutt. | heartleaf twistflower | Brassicaceae
|
| STCOL2 | Streptanthus coulteri (S. Wats.) Greene var. lemmonii Jepson | Caulanthus coulteri | Brassicaceae
|
| STCR8 | Streptanthus crassicaulis Torr. | Caulanthus crassicaulis var. crassicaulis | Brassicaceae
|