| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| ISECB | Isoetes echinospora Durieu var. braunii (Durieu) Engelm. | Isoetes tenella | Isoetaceae
|
| ISECH | Isoetes echinospora Durieu var. hesperia (C.F. Reed) A. L�ve | Isoetes tenella | Isoetaceae
|
| ISECM3 | Isoetes echinospora Durieu var. maritima (Underwood) A.A. Eat. | Isoetes maritima | Isoetaceae
|
| ISECM2 | Isoetes echinospora Durieu var. muricata (Durieu) Engelm. | Isoetes tenella | Isoetaceae
|
| ISECR | Isoetes echinospora Durieu var. robusta Engelm. | Isoetes tenella | Isoetaceae
|
| ISECS | Isoetes echinospora Durieu var. savilei Boivin | Isoetes tenella | Isoetaceae
|
| ISEC | Isoetes echinospora Durieu | Isoetes tenella | Isoetaceae
|
| ISENC | Isoetes engelmannii A. Braun var. caroliniana A.A. Eat. | Isoetes valida | Isoetaceae
|
| ISENG | Isoetes engelmannii A. Braun var. georgiana Engelm. | Isoetes appalachiana | Isoetaceae
|
| ISENG2 | Isoetes engelmannii A. Braun var. gracilis Engelm. | Isoetes engelmannii | Isoetaceae
|
| ISENV | Isoetes engelmannii A. Braun var. valida Engelm. | Isoetes valida | Isoetaceae
|
| ISEN | Isoetes engelmannii A. Braun | Appalachian quillwort | Isoetaceae
|
| ISFA | Isoetes �fairbrothersii J.D. Montgomery & W.C. Taylor | | Isoetaceae
|
| ISFLA | Isoetes flaccida Shuttlw. ex A. Braun var. alata N.E. Pfeiffer | southern quillwort | Isoetaceae
|
| ISFLC | Isoetes flaccida Shuttlw. ex A. Braun var. chapmanii Engelm. | Chapman's quillwort | Isoetaceae
|
| ISFLF | Isoetes flaccida Shuttlw. ex A. Braun var. flaccida | southern quillwort | Isoetaceae
|
| ISFL | Isoetes flaccida Shuttlw. ex A. Braun | southern quillwort | Isoetaceae
|
| ISFL2 | Isoetes flettii (A.A. Eat.) N.E. Pfeiffer | Isoetes occidentalis | Isoetaceae
|
| ISFO | Isoetes �foveolata A.A. Eat. ex Dodge (pro sp.) | | Isoetaceae
|
| ISGE | Isoetes georgiana N. Luebke | Georgia quillwort | Isoetaceae
|
| ISGR | Isoetes gravesii A.A. Eat. | Isoetes eatonii | Isoetaceae
|
| ISHA4 | Isoetes �harveyi A.A. Eat. (pro sp.) | | Isoetaceae
|
| ISHA5 | Isoetes hawaiiensis W.C. Taylor & W.H. Wagner | Hawai'i quillwort | Isoetaceae
|
| ISHE | Isoetes �heterospora A.A. Eat. (pro sp.) | | Isoetaceae
|
| ISHI2 | Isoetes �hickeyi W.C. Taylor & N. Luebke | | Isoetaceae
|
| ISHI3 | Isoetes hieroglyphica A.A. Eat. | Isoetes lacustris | Isoetaceae
|
| ISHOM | Isoetes howellii Engelm. var. minima (A.A. Eat.) Pfeiffer | Isoetes howellii | Isoetaceae
|
| ISHO | Isoetes howellii Engelm. | Howell's quillwort | Isoetaceae
|
| ISHY | Isoetes hyemalis D.F. Brunton | evergreenquillwort | Isoetaceae
|
| ISLAP2 | Isoetes lacustris L. ssp. paupercula (Engelm.) J. Feilberg | Isoetes occidentalis | Isoetaceae
|
| ISLAP | Isoetes lacustris L. var. paupercula Engelm. | Isoetes occidentalis | Isoetaceae
|
| ISLA | Isoetes lacustris L. | lake quillwort | Isoetaceae
|
| ISLI | Isoetes lithophila N.E. Pfeiffer | rock quillwort | Isoetaceae
|
| ISLO | Isoetes louisianensis Thieret | Louisiana quillwort | Isoetaceae
|
| ISMA | Isoetes macrospora Durieu | Isoetes lacustris | Isoetaceae
|
| ISMA3 | Isoetes maritima Underwood | maritime quillwort | Isoetaceae
|
| ISME | Isoetes melanopoda Gay & Durieu ex Durieu | blackfoot quillwort | Isoetaceae
|
| ISME3 | Isoetes melanospora Engelm. | blackspore quillwort | Isoetaceae
|
| ISMUM2 | Isoetes muricata Durieu ssp. maritima (Underwood) Hult�n | Isoetes maritima | Isoetaceae
|
| ISMUB | Isoetes muricata Durieu var. braunii (Durieu) C.F. Reed | Isoetes tenella | Isoetaceae
|
| ISMUH2 | Isoetes muricata Durieu var. hesperia C.F. Reed | Isoetes tenella | Isoetaceae
|
| ISMU2 | Isoetes muricata Durieu | Isoetes tenella | Isoetaceae
|
| ISNUO | Isoetes nuttallii A. Braun ex Engelm. var. orcuttii (A.A. Eat.) Clute | Isoetes orcuttii | Isoetaceae
|
| ISNU | Isoetes nuttallii A. Braun ex Engelm. | Nuttall's quillwort | Isoetaceae
|
| ISOC | Isoetes occidentalis Henderson | western quillwort | Isoetaceae
|
| ISOR | Isoetes orcuttii A.A. Eat. | Orcutt's quillwort | Isoetaceae
|
| ISPA2 | Isoetes paupercula (Engelm.) A.A. Eat. | Isoetes occidentalis | Isoetaceae
|
| ISPI | Isoetes piedmontana (N.E. Pfeiffer) C.F. Reed | Peidmont quillwort | Isoetaceae
|
| ISPI2 | Isoetes piperi A.A. Eat. | Isoetes occidentalis | Isoetaceae
|
| ISPR | Isoetes prototypus D.M. Britt. | spike quillwort | Isoetaceae
|
| ISPS | Isoetes �pseudotruncata D.M. Britton & D.F. Brunton | Isoetes maritima | Isoetaceae
|
| ISPY2 | Isoetes pygmaea Engelm. | Isoetes bolanderi | Isoetaceae
|
| ISRIA | Isoetes riparia Engelm. ex A. Braun var. amesii (A.A. Eat.) Proctor | Ames' quillwort | Isoetaceae
|
| ISRIC | Isoetes riparia Engelm. ex A. Braun var. canadensis Engelm. | Isoetes riparia var. riparia | Isoetaceae
|
| ISRIP | Isoetes riparia Engelm. ex A. Braun var. palmeri (A.A. Eat.) Proctor | Isoetes riparia var. riparia | Isoetaceae
|
| ISRIR2 | Isoetes riparia Engelm. ex A. Braun var. reticulata (A.A. Eat.) Proctor | Isoetes riparia var. amesii | Isoetaceae
|
| ISRIR | Isoetes riparia Engelm. ex A. Braun var. riparia | shore quillwort | Isoetaceae
|
| ISRIR3 | Isoetes riparia Engelm. ex A. Braun var. robbinsii (A.A. Eat.) Proctor | Isoetes riparia var. riparia | Isoetaceae
|
| ISRI | Isoetes riparia Engelm. ex A. Braun | shore quillwort | Isoetaceae
|
| ISSAA | Isoetes saccharata Engelm. var. amesii A.A. Eat. | Isoetes riparia var. amesii | Isoetaceae
|
| ISSA | Isoetes saccharata Engelm. | sugar quillwort | Isoetaceae
|
| ISSEM | Isoetes setacea Lam. ssp. muricata (Durieu) Holub | Isoetes tenella | Isoetaceae
|
| ISSE4 | Isoetes setacea Lam. p.p. | Isoetes tenella | Isoetaceae
|
| ISTE | Isoetes tegetiformans Rury | Merlin's grass | Isoetaceae
|
| ISTE5 | Isoetes tenella L�man | spiny-spore quillwort | Isoetaceae
|
| ISTR2 | Isoetes �truncata (A.A. Eat.) Clute (pro sp.) | | Isoetaceae
|
| ISTUH | Isoetes tuckermanii A. Braun var. harveyi (A.A. Eat.) Clute | Isoetes harveyi | Isoetaceae
|
| ISTUH2 | Isoetes tuckermanii A. Braun var. heterospora (A.A. Eat.) Clute | Isoetes heterospora | Isoetaceae
|
| ISTU | Isoetes tuckermanii A. Braun | Tuckerman's quillwort | Isoetaceae
|
| ISVA2 | Isoetes valida (Engelm.) Clute | strong quillwort | Isoetaceae
|
| ISVIP | Isoetes virginica N.E. Pfeiffer var. piedmontana N.E. Pfeiffer | Isoetes piedmontana | Isoetaceae
|
| ISVI | Isoetes virginica N.E. Pfeiffer | Virginia quillwort | Isoetaceae
|
| ISOET | Isoetes L. | quillwort | Isoetaceae
|
| ISCA6 | Isolepis carinata Hook. & Arn. ex Torr. | keeled bulrush | Cyperaceae
|
| ISCE | Isolepis cernua (Vahl) Roemer & J.A. Schultes | low bulrush | Cyperaceae
|
| ISFU | Isolepis funckii Steud. | Bulbostylis funckii | Cyperaceae
|
| ISHY2 | Isolepis hystrix (Thunb.) Nees | bottlebrush bulrush | Cyperaceae
|
| ISJU | Isolepis junciformis Kunth | Bulbostylis junciformis | Cyperaceae
|
| ISKO | Isolepis koilolepis Steud. | Isolepis carinata | Cyperaceae
|
| ISMO2 | Isolepis molesta (M.C. Johnston) S.G. Sm. | Gulf Coast bulrush | Cyperaceae
|
| ISSE2 | Isolepis setacea (L.) R. Br. | bristleleaf bulrush | Cyperaceae
|
| ISVE4 | Isolepis vestita Kunth | Bulbostylis vestita | Cyperaceae
|
| ISWA2 | Isolepis warei Torr. | Bulbostylis warei | Cyperaceae
|
| ISOLE | Isolepis R. Br. | bulrush | Cyperaceae
|
| ISARA | Isomeris arborea Nutt. var. angustata Parish | Cleome isomeris | Capparaceae
|
| ISARG | Isomeris arborea Nutt. var. globosa Coville | Cleome isomeris | Capparaceae
|
| ISARI | Isomeris arborea Nutt. var. insularis Jepson | Cleome isomeris | Capparaceae
|
| ISAR | Isomeris arborea Nutt. | Cleome isomeris | Capparaceae
|
| ISGU | Isonandra gutta Hook. f. | Palaquium gutta | Sapotaceae
|
| ISDI4 | Isopappus divaricatus (Nutt.) Torr. & Gray | Croptilon divaricatum | Asteraceae
|
| ISHO3 | Isopappus hookerianus Torr. & Gray | Croptilon hookerianum var. hookerianum | Asteraceae
|
| ISVA | Isopappus validus Rydb. | Croptilon hookerianum var. validum | Asteraceae
|
| ISFO3 | Isopogon formosus R. Br. | | Proteaceae
|
| ISOPO | Isopogon R. Br. ex Knight | cone flower | Proteaceae
|
| ISAL | Isopterygiopsis alpicola (Lindb. & Arnell) Heden�s | isopterygiopsis moss | Hypnaceae
|
| ISMU3 | Isopterygiopsis muelleriana (Schimp.) Iwats. | Mueller's isopterygiopsis moss | Hypnaceae
|
| ISPU70 | Isopterygiopsis pulchella (Hedw.) Iwats. | isopterygiopsis moss | Hypnaceae
|
| ISOPT2 | Isopterygiopsis Iwats. | isopterygiopsis moss | Hypnaceae
|
| ISAL3 | Isopterygium alpicola (Lindb.) & Arnell Nyh. | Isopterygiopsis alpicola | Hypnaceae
|
| ISBOG | Isopterygium borrerianum (C. M�ll.) Lindb. var. gracilens (Aust. ex Grout) Crum et al. | Pseudotaxiphyllum elegans | Hypnaceae
|
| ISBOT | Isopterygium borrerianum (C. M�ll.) Lindb. var. terrestre (Lindb.) Crum et al. | Pseudotaxiphyllum elegans | Hypnaceae
|