| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| SYLAH | Symphyotrichum lanceolatum (Willd.) Nesom ssp. hesperium (Gray) Nesom | white panicle aster | Asteraceae
|
| SYLAH7 | Symphyotrichum lanceolatum (Willd.) Nesom ssp. lanceolatum var. hirsuticaule (Semple & Chmielewski) Nesom | white panicle aster | Asteraceae
|
| SYLAI3 | Symphyotrichum lanceolatum (Willd.) Nesom ssp. lanceolatum var. interior (Wieg.) Nesom | white panicle aster | Asteraceae
|
| SYLAL4 | Symphyotrichum lanceolatum (Willd.) Nesom ssp. lanceolatum var. lanceolatum | white panicle aster | Asteraceae
|
| SYLAL5 | Symphyotrichum lanceolatum (Willd.) Nesom ssp. lanceolatum var. latifolium (Semple & Chmielewski) Nesom | white panicle aster | Asteraceae
|
| SYLAL6 | Symphyotrichum lanceolatum (Willd.) Nesom ssp. lanceolatum | white panicle aster | Asteraceae
|
| SYLA6 | Symphyotrichum lanceolatum (Willd.) Nesom | white panicle aster | Asteraceae
|
| SYLAA | Symphyotrichum lateriflorum (L.) A.& D. L�ve var. angustifolium (Wieg.) Nesom | calico aster | Asteraceae
|
| SYLAF | Symphyotrichum lateriflorum (L.) A.& D. L�ve var. flagellare (Shinners) Nesom | calico aster | Asteraceae
|
| SYLAH4 | Symphyotrichum lateriflorum (L.) A.& D. L�ve var. hirsuticaule (DC.) Nesom | calico aster | Asteraceae
|
| SYLAH5 | Symphyotrichum lateriflorum (L.) A.& D. L�ve var. horizontale (Desf.) Nesom | calico aster | Asteraceae
|
| SYLAL7 | Symphyotrichum lateriflorum (L.) A.& D. L�ve var. lateriflorum | calico aster | Asteraceae
|
| SYLAS | Symphyotrichum lateriflorum (L.) A.& D. L�ve var. spatelliforme (Burgess) Nesom | calico aster | Asteraceae
|
| SYLAT | Symphyotrichum lateriflorum (L.) A.& D. L�ve var. tenuipes (Wieg.) Nesom | calico aster | Asteraceae
|
| SYLA4 | Symphyotrichum lateriflorum (L.) A.& D. L�ve | calico aster | Asteraceae
|
| SYLE2 | Symphyotrichum lentum (Greene) Nesom | Suisun Marsh aster | Asteraceae
|
| SYLO3 | Symphyotrichum longifolium (Lam.) Nesom, as to type | Symphyotrichum novi-belgii var. novi-belgii | Asteraceae
|
| SYLO6 | Symphyotrichum longifolium sensu Nesom, non Lam. | Symphyotrichum robynsianum | Asteraceae
|
| SYLO4 | Symphyotrichum �longulum (Sheldon) Nesom | | Asteraceae
|
| SYLO2 | Symphyotrichum lowrieanum (Porter) Nesom | Lowrie's blue wood aster | Asteraceae
|
| SYMO2 | Symphyotrichum molle (Rydb.) Nesom | soft aster | Asteraceae
|
| SYNO2 | Symphyotrichum novae-angliae (L.) Nesom | New England aster | Asteraceae
|
| SYNOC | Symphyotrichum novi-belgii (L.) Nesom var. crenifolium (Fern.) J. Labrecque & L. Brouillet | Newfoundland aster | Asteraceae
|
| SYNOE | Symphyotrichum novi-belgii (L.) Nesom var. elodes (Torr. & Gray) Nesom | New York aster | Asteraceae
|
| SYNOL | Symphyotrichum novi-belgii (L.) Nesom var. litoreum (Gray) Nesom | Symphyotrichum praealtum var. praealtum | Asteraceae
|
| SYNON | Symphyotrichum novi-belgii (L.) Nesom var. novi-belgii | New York aster | Asteraceae
|
| SYNOV | Symphyotrichum novi-belgii (L.) Nesom var. villicaule (Gray) J. Labrecque & L. Brouillet | hairy New York aster | Asteraceae
|
| SYNO3 | Symphyotrichum novi-belgii (L.) Nesom | New York aster | Asteraceae
|
| SYOB | Symphyotrichum oblongifolium (Nutt.) Nesom | aromatic aster | Asteraceae
|
| SYONG | Symphyotrichum ontarione (Wieg.) Nesom var. glabratum (Semple) L. Brouillet & Bouchard | Symphyotrichum ontarione | Asteraceae
|
| SYON | Symphyotrichum ontarione (Wieg.) Nesom | bottomland aster | Asteraceae
|
| SYOOO | Symphyotrichum oolentangiense (Riddell) Nesom var. oolentangiense | skyblue aster | Asteraceae
|
| SYOOP | Symphyotrichum oolentangiense (Riddell) Nesom var. poaceum (Burgess) Nesom | skyblue aster | Asteraceae
|
| SYOO | Symphyotrichum oolentangiense (Riddell) Nesom | skyblue aster | Asteraceae
|
| SYPA10 | Symphyotrichum parviceps (Burgess) Nesom | smallhead aster | Asteraceae
|
| SYPAG | Symphyotrichum patens (Ait.) Nesom var. gracile (Hook.) Nesom | late purple aster | Asteraceae
|
| SYPAP2 | Symphyotrichum patens (Ait.) Nesom var. patens | late purple aster | Asteraceae
|
| SYPAP | Symphyotrichum patens (Ait.) Nesom var. patentissimum (Lindl. ex DC.) Nesom | late purple aster | Asteraceae
|
| SYPA11 | Symphyotrichum patens (Ait.) Nesom | late purple aster | Asteraceae
|
| SYPH3 | Symphyotrichum phlogifolium (Muhl. ex Willd.) Nesom | thinleaf late purple aster | Asteraceae
|
| SYPIP3 | Symphyotrichum pilosum (Willd.) Nesom var. pilosum | hairy white oldfield aster | Asteraceae
|
| SYPIP2 | Symphyotrichum pilosum (Willd.) Nesom var. pringlei (Gray) Nesom | Pringle's aster | Asteraceae
|
| SYPI2 | Symphyotrichum pilosum (Willd.) Nesom | hairy white oldfield aster | Asteraceae
|
| SYPO4 | Symphyotrichum porteri (Gray) Nesom | smooth white aster | Asteraceae
|
| SYPO5 | Symphyotrichum potosinum (Gray) Nesom | Santa Rita Mountain aster | Asteraceae
|
| SYPRA | Symphyotrichum praealtum (Poir.) Nesom var. angustior (Wieg.) Nesom | willowleaf aster | Asteraceae
|
| SYPRN | Symphyotrichum praealtum (Poir.) Nesom var. nebraskense (Britt.) Nesom | Nebraska aster | Asteraceae
|
| SYPRP | Symphyotrichum praealtum (Poir.) Nesom var. praealtum | willowleaf aster | Asteraceae
|
| SYPRS | Symphyotrichum praealtum (Poir.) Nesom var. subasperum (Lindl.) Nesom | willowleaf aster | Asteraceae
|
| SYPRT | Symphyotrichum praealtum (Poir.) Nesom var. texicola (Wieg.) Nesom | Symphyotrichum praealtum var. praealtum | Asteraceae
|
| SYPR5 | Symphyotrichum praealtum (Poir.) Nesom | willowleaf aster | Asteraceae
|
| SYPR7 | Symphyotrichum pratense (Raf.) Nesom | barrens silky aster | Asteraceae
|
| SYPR6 | Symphyotrichum prenanthoides (Muhl. ex Willd.) Nesom | crookedstem aster | Asteraceae
|
| SYPR4 | Symphyotrichum priceae (Britt.) Nesom | lavender oldfield aster | Asteraceae
|
| SYPUC | Symphyotrichum puniceum (L.) A.& D. L�ve var. calderi (Boivin) Nesom | Symphyotrichum puniceum var. puniceum | Asteraceae
|
| SYPUP | Symphyotrichum puniceum (L.) A.& D. L�ve var. puniceum | purplestem aster | Asteraceae
|
| SYPUS | Symphyotrichum puniceum (L.) A.& D. L�ve var. scabricaule (Shinners) Nesom | purplestem aster | Asteraceae
|
| SYPU | Symphyotrichum puniceum (L.) A.& D. L�ve | purplestem aster | Asteraceae
|
| SYRAS | Symphyotrichum racemosum (Ell.) Nesom var. ?subdumosum (Wieg.) Nesom | Symphyotrichum racemosum | Asteraceae
|
| SYRA5 | Symphyotrichum racemosum (Ell.) Nesom | smooth white oldfield aster | Asteraceae
|
| SYRE3 | Symphyotrichum retroflexum (Lindl. ex DC.) Nesom | rigid whitetop aster | Asteraceae
|
| SYRO3 | Symphyotrichum robynsianum (Rouss.) L. Brouillet & Labrecque | longleaf aster | Asteraceae
|
| SYSA4 | Symphyotrichum sagittifolium (Wedemeyer ex Willd.) Nesom | Symphyotrichum cordifolium | Asteraceae
|
| SYSC2 | Symphyotrichum �schistosum (Steele) Nesom | | Asteraceae
|
| SYSE2 | Symphyotrichum sericeum (Vent.) Nesom | western silver aster | Asteraceae
|
| SYSH | Symphyotrichum shortii (Lindl.) Nesom | Short's aster | Asteraceae
|
| SYSI3 | Symphyotrichum simmondsii (Small) Nesom | Simmonds' aster | Asteraceae
|
| SYSI2 | Symphyotrichum simplex (Willd.) A.& D. L�ve | Symphyotrichum lanceolatum ssp. lanceolatum var. lanceolatum | Asteraceae
|
| SYSPF | Symphyotrichum spathulatum (Lindl.) Nesom var. fremontii (Torr. & Gray) Nesom | Symphyotrichum spathulatum var. spathulatum | Asteraceae
|
| SYSPI | Symphyotrichum spathulatum (Lindl.) Nesom var. intermedium (Gray) Nesom | larger western mountain aster | Asteraceae
|
| SYSPS | Symphyotrichum spathulatum (Lindl.) Nesom var. spathulatum | western mountain aster | Asteraceae
|
| SYSPY | Symphyotrichum spathulatum (Lindl.) Nesom var. yosemitanum (Gray) Nesom | western bog aster | Asteraceae
|
| SYSP | Symphyotrichum spathulatum (Lindl.) Nesom | western mountain aster | Asteraceae
|
| SYSQ | Symphyotrichum squamatum (Spreng.) Nesom | southeastern annual saltmarsh aster | Asteraceae
|
| SYSU3 | Symphyotrichum subgeminatum (Fern.) Nesom | Symphyotrichum ciliolatum | Asteraceae
|
| SYSUG | Symphyotrichum subspicatum (Nees) Nesom var. grayi (Suksdorf) Nesom | Gray's aster | Asteraceae
|
| SYSUS | Symphyotrichum subspicatum (Nees) Nesom var. subspicatum | Douglas aster | Asteraceae
|
| SYSU4 | Symphyotrichum subspicatum (Nees) Nesom | Douglas aster | Asteraceae
|
| SYSU5 | Symphyotrichum subulatum (Michx.) Nesom | eastern annual saltmarsh aster | Asteraceae
|
| SYTE6 | Symphyotrichum tenuifolium (L.) Nesom | perennial saltmarsh aster | Asteraceae
|
| SYTR | Symphyotrichum tradescantii (L.) Nesom | shore aster | Asteraceae
|
| SYTU2 | Symphyotrichum turbinellum (Lindl.) Nesom | smooth violet prairie aster | Asteraceae
|
| SYUN | Symphyotrichum undulatum (L.) Nesom | waxyleaf aster | Asteraceae
|
| SYUR | Symphyotrichum urophyllum (Lindl.) Nesom | white arrowleaf aster | Asteraceae
|
| SYWA | Symphyotrichum walteri (Alexander) Nesom | Walter's aster | Asteraceae
|
| SYWE | Symphyotrichum welshii (Cronq.) Nesom | Welsh's aster | Asteraceae
|
| SYWO3 | Symphyotrichum �woldenii (Rydb.) Nesom | | Asteraceae
|
| SYYU | Symphyotrichum yukonense (Cronq.) Nesom | Yukon aster | Asteraceae
|
| SYMPH4 | Symphyotrichum Nees | aster | Asteraceae
|
| SYRA | Symphysia racemosa (Vahl) Stearn | leatherleaf eelvine | Ericaceae
|
| SYMPH3 | Symphysia K. Presl | symphysia | Ericaceae
|
| SYAS2 | Symphytum asperrimum Donn ex Sims | Symphytum asperum | Boraginaceae
|
| SYAS | Symphytum asperum Lepechin | prickly comfrey | Boraginaceae
|
| SYOFU | Symphytum officinale L. ssp. uliginosum (Kern.) Nyman | Symphytum officinale | Boraginaceae
|
| SYOF | Symphytum officinale L. | common comfrey | Boraginaceae
|
| SYPE3 | Symphytum peregrinum auct. non Ledeb. | Symphytum uplandicum | Boraginaceae
|
| SYTU | Symphytum tuberosum L. | tuberous comfrey | Boraginaceae
|
| SYUL | Symphytum uliginosum Kern. | Symphytum officinale | Boraginaceae
|
| SYUP | Symphytum �uplandicum Nyman (pro sp.) | | Boraginaceae
|
| SYMPH2 | Symphytum L. | comfrey | Boraginaceae
|
| SYFO | Symplocarpus foetidus (L.) Salisb. ex Nutt. | skunk cabbage | Araceae
|