Below is our list of Maine’s rare plants. Fact sheets are available for download for most of the plants in Adobe PDF format. If you need Adobe Reader, you may download it from Adobe’s web site. You may also call (207) 287-8044 to receive these factsheets by mail or fax.
| Scientific Name | Common Name | State Rank | Global Rank | Federal Status | State Status | Proposed State Status | Fact Sheet |
| Acalypha virginica | Three-seeded mercury | SH | G5 | | PE | | |
| Adiantum aleuticum | Aleutian maidenhair fern | S1 | G5? | | E | |  download |
| Adlumia fungosa | Allegheny vine | S1 | G4 | | T | | download |
| Agalinis maritima | Saltmarsh false-foxglove | S3 | G5 | | SC | | download |
| Agalinis neoscotica | Nova scotia false-foxglove | S1 | G4 | | T | | download |
| Agalinis purpurea | Large-purple false-foxglove | S1 | G5 | | E | | |
| Agrostis mertensii | Boreal bentgrass | S2 | G5 | | T | | download |
| Aletris farinosa | Unicorn root | SX | G5 | | PE | | |
| Allium canadense | Wild garlic | S2 | G5 | | SC | | download |
| Allium tricoccum | Wild leek | S3 | G5 | | SC | | download |
| Amelanchier nantucketensis | Nantucket shadbush | S2 | G3Q | | T | | download |
| Amelanchier sanguinea var gaspensis | Gaspe shadbush | S2 | G5T4? | | SC | | download |
| Amerorchis rotundifolia | Small round-leaved orchis | S2 | G5 | | T | | download |
| Anemone multifida | Cut-leaved anemone | S1 | G5 | | T | | download |
| Arabis laevigata | Smooth rockcress | S1 | G5 | | T | | download |
| Arabis missouriensis | Missouri rockcress | S1 | G5?Q | | T | | download |
| Arctostaphylos alpina | Alpine bearberry | S1 | G5 | | T | | download |
| Arnica lanceolata | Hairy arnica | S2 | G3 | | T | | download |
| Artemisia campestris ssp borealis | Canadian wormwood | SH | G5T5 | (PS) | PE | | |
| artemisia campestris ssp caudata | Beach wormwood | S1S2 | G5T5 | | SC | | |
| Asarum canadense | Wild ginger | S1S2 | G5 | | T | | download |
| Asclepias tuberosa | Butterfly weed | SX | G5? | | PE | | |
| Asplenium platyneuron | Ebony spleenwort | S2 | G5 | | SC | | download |
| Asplenium rhizophyllum | Walking fern | SX | G5 | | PE | | |
| Asplenium trichomanes-ramosum | Green spleenwort | S1 | G4 | | E | | download |
| Aster divaricatus | White wood aster | S3 | G5 | | T | SC | download |
| Aster schreberi | Schreber's aster | SX | G4 | | PE | | |
| Astragalus alpinus | Alpine milk-vetch | S3 | G5T3 | | SC | | download |
| Astragalus eucosmus | Elegant milk-vetch | SX | G5 | | PE | | |
| Astragalus robbinsii | Robbins' milk-vetch | S1 | G5T5 | | SC | | |
| Aureolaria pedicularia | Fern-leaved false foxglove | S3 | G5 | | SC | | download |
| Baptisia tinctoria | Wild indigo | S1 | G5 | | E | | download |
| Barbarea orthoceras | American winter-cress | SH | G5 | | PE | | |
| Bartonia paniculata | Screwstem | S1 | G5 | | T | | download |
| Betula glandulosa | Tundra dwarf birch | S1 | G5 | | E | | download |
| Betula minor | Dwarf white birch | S1 | G4Q | | E | | download |
| Betula pumila | Swamp birch | S2S3 | G5 | | SC | | download |
| Bidens eatonii | Eaton's bur-marigold | S2 | G2G3 | | SC | | download |
| Bidens hyperborea | Estuary bur-marigold | S3 | G4 | | SC | | download |
| Bolboschoenus novae-angliae | Marsh bulrush | S1 | G5 | | SC | | download |
| Bolboschoenus robustus | Saltmarsh bulrush | S2 | G5 | | SC | | |
| Botrychium lunaria | Moonwort | S1 | G5 | | E | | download |
| Botrychium oneidense | Blunt-lobed grape fern | SU | G4Q | | SC | | |
| Botrychium pallidum | Pale moonwork | S1 | G3 | | SC | | |
| Bromus kalmii | Wild Chess | SH | G5 | | PE | | |
| Bromus pubescens | Hairy wood brome-grass | S2 | G5 | | SC | | |
| Calamagrostis cinnoides | Small reed-grass | S3 | G5 | | SC | | download |
| Calamagrostis pickeringii | Pickering's reed bent-grass | S1 | G4 | | T | | download |
| Calamagrostis stricta ssp inexpansa | New england northern reed grass | S1 | G5T5 | | E | | download |
| Calamagrostis stricta ssp stricta | Neglected reed-grass | S2 | G5T5 | | T | | download |
| Callitriche terrestris | terrestrial water-starwort | SU | G5 | | SC | | |
| Calystegia spithamaea | Upright bindweed | S2 | G4G5 | | T | | download |
| Cardamine maxima | Large toothwort | S1 | G5 | | SC | | download |
| Cardamine bellidifolia | Alpine bitter-cress | S1 | G5 | | E | | |
| Cardamine concatenata | Cut-leaved toothwort | S1 | G5 | | E | | download |
| Cardamine longii | Long's bitter-cress | S2 | G3 | | T | | download |
| Carex adusta | Swarthy sedge | S2 | G5 | | E | | download |
| Carex alopecoidea | Foxtail sedge | SH | G5 | | PE | | download |
| Carex atherodes | Awned sedge | S1 | G5 | | E | | download |
| Carex atratiformis | Black sedge | S2S3 | G5 | | SC | | download |
| Carex baileyi | Bailey's sedge | SH | G4 | | PE | | download |
| Carex bicknellii | Bicknell's sedge | S1 | G5 | | E | | download |
| Carex bigelowii | Bigelow's sedge | S2 | G5 | | SC | | download |
| Carex bullata | Button Sedge | S2 | G5 | | SC | | |
| Carex bushii | Bush's sedge | SX | G4 | | PE | | |
| Carex capillaris | Capillary sedge | S2 | G5 | | SC | | download |
| Carex crawei | Crawe's sedge | SX | G5 | | PE | | download |
| Carex eburnea | Ebony sedge | S1 | G5 | | E | | download |
| Carex garberi | Garber's sedge | S2 | G5 | | SC | | download |
| Carex granularis | Meadow Sedge | S1 | G5 | | T | | |
| Carex grisea | Narrowleaf sedge | SH | G5? | | SC | | download |
| Carex gynocrates | Northern bog sedge | S2 | G5 | | SC | | download |
| Carex hirtifolia | Pubescent sedge | S2 | G5 | | SC | | |
| Carex laevivaginata | Smooth-sheathed sedge | S1 | G5 | | SC | | download |
| Carex laxiculmis | Spreading sedge | S2 | G5 | | E | | download |
| Carex livida | Livid sedge | S2 | G5T5 | | SC | | download |
| Carex macloviana | Falkland island sedge | SU | G3G5 | | PE | | |
| Carex muehlenbergii | Muhlenberg sedge | S1 | G5T5? | | E | | download |
| Carex norvegica | Intermediate sedge | S1 | G5T5? | | E | | download |
| Carex oronensis | Orono sedge | S3 | G3 | | T | SC | download |
| Carex polymorpha | Variable sedge | S1 | G3 | | E | | download |
| Carex prairea | Prairie sedge | S1 | G5? | | T | | download |
| Carex praticola | Northern meadow sedge | SX | G5 | | PE | | |
| Carex rariflora | Loose-flowered sedge | SH | G5 | | PE | | download |
| Carex recta | Salt-marsh sedge | SH | G4 | | PE | E | download |
| Carex rostrata | Blueleaf sedge | S2 | G5 | | SC | | download |
| Carex saxatilis | Russett sedge | S1 | G5 | | E | | download |
| Carex scirpoidea | Bulrush sedge | S2 | G5 | | SC | | download |
| Carex siccata | Dry land sedge | S2 | G5 | | SC | | download |
| Carex sparganioides | Bur-reed sedge | S1 | G5 | | E | | download |
| Carex sterilis | Dioecious sedge | S3 | G4 | | SC | | download |
| Carex tenuiflora | Sparse-flowered sedge | S3 | G5 | | SC | | download |
| Carex typhina | Cat-tail sedge | S1 | G5 | | E | | download |
| Carex vacillans | Brackish sedge | S2 | GNR | | E | | download |
| Carex vestita | Clothed sedge | S1 | G5 | | E | | download |
| Carya cordiformis | Bitternut hickory | S1 | G5 | | E | | download |
| Castanea dentata | American chestnut | S4 | G4 | | SC | | download |
| Castilleja septentrionalis | Northern painted cup | S3 | G5 | | SC | | download |
| Ceanothus americanus | New jersey tea | S1S2 | G5 | | T | | download |
| Cenchrus longispinus | Long-spined sandbur | SH | G5 | | PE | | download |
| Chamaecyparis thyoides | Atlantic white-cedar | S2 | G4 | | SC | | download |
| Chenopodium foggii | Fogg's goosefoot | S1 | G3Q | | SC | | download |
| Chenopodium humile | Marshland goosefoot | SH | G5 | | PE | | |
| Chenopodium rubrum | Coast-blite goosefoot | S1 | G5 | | T | | download |
| Chimaphila maculata | Spotted wintergreen | S2 | G5 | | E | | download |
| Cirsium horridulum | Yellow Thistle | SH | G5 | | PE | | |
| Clematis occidentalis | Purple clematis | S3 | G5T5 | | SC | | download |
| Clethra alnifolia | Sweet pepper-bush | S2 | G5 | | SC | | download |
| Corallorhiza odontorhiza | Autumn coral-root | S1 | G5 | | E | | download |
| Cornus florida | Flowering dogwood | S1 | G5 | | E | | download |
| Crassula aquatica | Pygmyweed | S2S3 | G5 | | SC | | download |
| Cryptogramma stelleri | Slender cliffbrake | S1 | G5 | | T | | download |
| Cryptotaenia canadensis | Wild chervil | SH | G5 | | PE | | download |
| Cynoglossum virginianum | Northern wild comfrey | S1 | G5T4T5 | | E | | download |
| Cyperus erythrorhizos | Red-root flatsedge | SH | G5 | | PE | | download |
| Cyperus houghtonii | Houghton's umbrella-sedge | SH | G4? | | PE | | |
| Cyperus squarrosus | Awned sedge | S2 | G5 | | SC | | download |
| Cypripedium arietinum | Ram's-head lady's-slipper | S1 | G3 | | E | | download |
| Cypripedium reginae | Showy lady's-slipper | S3 | G4 | | T | | download |
| Descurainia incana | Richardson's tansy-mustard | SH | G5T5? | | PE | | download |
| Diapensia lapponica | Lapland diapensia | S2 | G5 | | SC | | download |
| Dicentra canadensis | Squirrel-corn | S1 | G5 | | T | | download |
| Diphasiastrum sitchense | Alaskan clubmoss | S1 | G5 | | T | | download |
| Draba arabisans | Rock whitlow-grass | S1 | G4 | | T | | download |
| Draba cana | Lance-leaved draba | S1 | G5 | | E | | download |
| Draba glabella | Rock whitlow-grass | S1 | G4G5 | | E | | download |
| Drosera anglica | English sundew | S1 | G5 | | E | | download |
| Drosera linearis | Slender-leaved sundew | S1 | G4 | | E | | download |
| Dryopteris filix-mas | Male fern | S1 | G5 | | E | | download |
| Dryopteris fragrans | Fragrant cliff wood-fern | S3 | G5 | | SC | | download |
| Dryopteris goldiana | Goldie's wood-fern | S2 | G4 | | SC | | download |
| Eleocharis aestuum | Bay spikerush | S2 | G3 | | SC | | download |
| Eleocharis engelmannii | Engelmann's spikerush | SH | G4G5Q | | PE | | download |
| Eleocharis nitida | Slender spikerush | SU | G3G4 | | SC | | |
| Eleocharis quinqueflora | Few-flowered spikerush | S2 | G5 | | SC | | download |
| Eleocharis rostellata | Beaked spikerush | S1 | G5 | | SC | | download |
| Eleocharis tuberculosa | Long-tubercled spike-rush | S1 | G5 | | E | | download |
| Elymus hystrix | Bottlebrush grass | S3 | G5 | | SC | | download |
| Elymus macgregorii | MacGregor's wild rye | S2 | GNR | | SC | | download |
| Epilobium anagallidifolium | Alpine willow-herb | S1 | G5 | | E | | download |
| Epilobium hornemannii | Hornemann's willow-herb | S1 | G5 | | E | | download |
| Epilobium lactiflorum | White-flower Willow-herb | SH | G5 | PE | | | |
| Eragrostis capillaris | Tiny love-grass | SH | G5 | | PE | | download |
| Eragrostis hypnoides | Teal love grass | SH | G5 | | PE | | |
| Erigeron hyssopifolius | Hyssop-leaved fleabane | S2 | G5 | | SC | | download |
| Eriocaulon parkeri | Parker's pipewort | S3 | G3 | | SC | | download |
| Eupatorium fistulosum | Hollow joe-pye weed | S2 | G5? | | SC | | download |
| Eupatorium rotundifolium | Hairy boneset | S1 | G5T5 | | SC | | download |
| Euphrasia oakesii | Oakes' eyebright | S1 | G4 | | E | | download |
| Euthamia tenuifolia | Narrow-leaved goldenrod | S2 | G5T5 | | T | | download |
| Festuca prolifera | Arctic red fescue | S1 | GU | | E | | download |
| Fimbristylis autumnalis | Fall fimbry | S2S3 | G5 | | T | | download |
| Galearis spectabilis | Showy orchis | S1 | G5 | | E | | download |
| Galium brevipes | Limestone swamp bedstraw | SH | G4? | | SC | | download |
| Galium kamtschaticum | Boreal bedstraw | S2 | G5 | | T | | download |
| Galium labradoricum | Bog bedstraw | S2 | G5 | | SC | | download |
| Galium obtusum | Blunt-leaved bedstraw | SX | G5 | | PE | | |
| Gamochaeta purpurea | Purple cudweed | SX | G5 | | PE | | |
| Gentiana rubricaulis | Red-stemmed gentian | S1 | G4? | | SC | | |
| Gentianella amarella | Northern gentian | S1 | G5T5 | | E | | download |
| Gentianella quinquefolia | Stiff gentian | SH | G5 | | PE | | download |
| Geocaulon lividum | Northern comandra | S3 | G5 | | SC | | download |
| Glyceria acutiflora | Sharp-scaled manna-grass | S1 | G5 | | E | | download |
| Goodyera oblongifolia | Giant rattlesnake-plantain | S1 | G5? | | E | | download |
| Hackelia deflexa | Northern stickseed | S1 | G5T5 | | E | | download |
| Harrimanella hypnoides | Moss bell-heather | S1 | G5 | | T | | download |
| Hedysarum alpinum | Alpine sweet-broom | S3 | G5T5? | | SC | | download |
| Hepatica nobilis var acuta | Sharp-lobed hepatica | SX | G5T5 | | PE | | |
| Hieracium gronovii | Hairy hawkweed | SX | G5 | | PE | | |
| Hieracium robinsonii | Robinson's hawkweed | S1 | G2G3 | | E | | download |
| Hieracium venosum | Rattlesnake hawkweed | S1 | G5T4Q | | E | | download |
| Hierochloe alpina | Alpine sweet-grass | S1 | G5 | | T | | download |
| Hottonia inflata | Featherfoil | S1 | G4 | | T | | download |
| Houstonia longifolia | Long-leaved bluet | S2S3 | G4G5TNR | | SC | | download |
| Huperzia appalachiana | Appalachian fir-clubmoss | S2 | G4G5 | | SC | | download |
| Huperzia selago | Alpine clubmoss | S2 | G5 | | T | | download |
| Hypericum ascyron | Great st john's-wort | S1 | G4 | | E | | download |
| Hypoxis hirsuta | Yellow star grass | SX | G5 | | PE | | |
| Ilex glabra | Ink-berry | S1 | G5 | | E | | download |
| Ilex laevigata | Smooth winterberry holly | S3 | G5 | | SC | | download |
| Impatiens pallida | Pale jewel-weed | S2 | G5 | | SC | | download |
| Iris prismatica | Slender blue flag | S2 | G4G5 | | T | | download |
| Isoetes acadiensis | Acadian quillwort | S2 | G3Q | | SC | | download |
| Isoetes prototypus | Prototype quillwort | S1 | G2G3 | | T | E | download |
| Isoetes riparia | Shore quillwort | SH | G5? | | PE | | download |
| Isotria medeoloides | Small whorled pogonia | S2 | G2 | LT | E | | download |
| Isotria verticillata | Large whorled pogonia | SX | G5 | | PE | | download |
| Iva frutescens | Marsh-elder | S1 | G5T5 | | E | | download |
| Juncus alpinoarticulatus | Alpine rush | S3 | G5T5? | | SC | | download |
| Juncus secundus | Secund rush | S1 | G5? | | T | | download |
| Juncus stygius | Moor rush | S2 | G5T5 | | SC | | download |
| Juncus subtilis | Slender rush | S1 | G4 | | T | | download |
| Juncus torreyi | Torrey's rush | SH | G5 | | PE | | download |
| Juncus vaseyi | Vasey rush | S1 | G5? | | E | | download |
| Kalmia latifolia | Mountain-laurel | S2 | G5 | | SC | | download |
| Krigia virginica | Dwarf dandelion | S1 | G5 | | T | | download |
| Lechea tenuifolia | Slender pinweed | SX | G5 | | PE | | |
| Lespedeza hirta | Hairy bush-clover | S1 | G5T5? | | E | E | download |
| Liatris scariosa | Northern blazing star | S1 | G5?T3 | | T | | download |
| Lilaeopsis chinensis | Lilaeopsis | S2 | G5 | | T | | download |
| Limosella australis | Mudwort | S3 | G4G5 | | SC | | download |
| Lindera benzoin | Spicebush | S3 | G5 | | SC | | download |
| Lindernia dubia var anagallidea | Slender false pimpernel | SH | G5T4 | | PE | | download |
| Lipocarpha micrantha | Dwarf bulrush | S1 | G4 | | T | | download |
| Listera auriculata | Auricled twayblade | S2 | G3G4 | | T | | download |
| Lobelia siphilitica | Great blue lobelia | SX | G5 | | PE | | |
| Loiseleuria procumbens | Alpine azalea | S1 | G5 | | T | | download |
| Lomatogonium rotatum | Marsh felwort | S1 | G5 | | T | | download |
| Lonicera dioica | Mountain honeysuckle | S2 | G5 | | E | | download |
| Lonicera oblongifolia | Swamp fly-honeysuckle | S3 | G4 | | SC | | download |
| Lupinus perennis | Wild lupine | SX | G5T4? | | PE | | download |
| Luzula confusa | Northern wood-rush | S1 | G5 | | E | | download |
| Luzula spicata | Spiked wood-rush | S1 | G5 | | T | E | download |
| Lycopodiella alopecuroides | Southern Bog Clubmoss | S1 | G5 | | E | | download |
| Malaxis monophyllos | White adder's-mouth | S1 | G5 | | E | | download |
| Mikania scandens | Climbing hempweed | SH | G5 | | PE | | download |
| Mimulus ringens var colpophilus | Estuary monkeyflower | S2 | G5T2Q | | SC | | download |
| Minuartia glabra | Smooth sandwort | S3 | G4 | | SC | | download |
| Minuartia groenlandica | Mountain sandwort | S3 | G5 | | SC | | download |
| Minuartia rubella | Arctic sandwort | S1 | G5 | | E | | download |
| Montia fontana | Blinks | S2 | G5 | | SC | | download |
| Muhlenbergia richardsonis | Soft-leaf muhly | S3 | G5 | | SC | | download |
| Muhlenbergia sobolifera | Cliff muhly | SH | G5 | | PE | | download |
| Nuphar advena | Yellow pond-lily | S2 | G5T5 | | SC | | download |
| Nymphaea leibergii | Pygmy water-lily | S1S2 | G5 | | T | | download |
| Oenothera nutans | Riverbank Evening Primrose | SH | G4 | | PE | | |
| Omalotheca supina | Alpine cudweed | S1 | G5 | | E | | download |
| Ophioglossum pusillum | Adder's tongue fern | S1 | G5 | | SC | | download |
| Oryzopsis canadensis | Canada mountain-ricegrass | S2 | G5 | | SC | | download |
| Osmorhiza depauperata | Blunt-fruited sweet-cicely | SH | G5 | | PE | | |
| Oxytropis campestris | St john oxytrope | S1 | G5T4 | | T | | download |
| Panax quinquefolius | American ginseng | S3 | G3G4 | | E | | download |
| Parietaria pensylvanica | Pennsylvania pellitory | SX | G5 | | PE | | |
| Paronychia argyrocoma | Silverling | S1 | G4 | | T | | download |
| Pedicularis furbishiae | Furbish's lousewort | S2 | G2 | LE | E | | download |
| Persicaria robustior | Stout smartweed | SH | G4G5 | | PE | | |
| Persicaria vivipara | Alpine bistort | S1 | G5 | | E | | download |
| Phegopteris hexagonoptera | Broad beech fern | S2 | G5 | | SC | | download |
| Phleum alpinum | Mountain timothy | S2 | G5 | | T | | download |
| Phryma leptostachya | Lopseed | SH | G5 | | PE | | download |
| Phyllodoce caerulea | Mountain heath | S1 | G5 | | T | | download |
| Pinguicula vulgaris | Common butterwort | S1 | G5 | | E | | download |
| Platanthera flava | Pale green orchis | S2 | G4T4Q | | SC | | download |
| Platanthera leucophaea | Prairie white-fringed orchid | S1 | G3 | LT | E | | download |
| Platanus occidentalis | Sycamore | SX | G5 | | PE | | |
| Poa fernaldiana | Wavy bluegrass | S1 | G3 | | E | | download |
| Poa glauca | White bluegrass | S1 | G5 | | T | | download |
| Polemonium vanbruntiae | Jacobs ladder | S1 | G3G4 | | E | | download |
| Polygala cruciata | Marsh milkwort | SH | G5T4 | | PE | | download |
| Polygala senega | Seneca snakeroot | S1 | G4G5 | | T | | download |
| Polygonum douglasii | Douglas' knotweed | S2 | G5 | | SC | | download |
| Polygonum tenue | Slender knotweed | SH | G5 | | PE | | |
| Potamogeton friesii | Fries' pondweed | S1 | G4 | | E | | download |
| Potamogeton pulcher | Spotted pondweed | S1 | G5 | | T | | download |
| Potamogeton strictifolius | Straight-leaved pondweed | S1 | G5 | | T | | download |
| Potamogeton vaseyi | Vasey's pondweed | S2 | G4 | | SC | | download |
| Prenanthes boottii | Boott's rattlesnake root | S1 | G2 | | E | | download |
| Prenanthes nana | Dwarf rattlesnake root | S1 | G5 | | E | | download |
| Prenanthes racemosa | Glaucous rattlesnake root | S3 | G5 | | SC | | download |
| Primula laurentiana | Bird's-eye primrose | S2 | G5 | | SC | | download |
| Primula mistassinica | Mistassini primrose | S3 | G5 | | SC | | download |
| Proserpinaca pectinata | Comb-leaved mermaid-weed | S1 | G5 | | E | | download |
| Prunus maritima | Beach plum | S1 | G4 | | E | | download |
| Pseudognaphalium helleri | Small rabbit tobacco | SH | G4G5T3? | | PE | | download |
| Pycnanthemum muticum | Blunt mountain-mint | SH | G5 | | PE | | download |
| Pyrola minor | Lesser wintergreen | S2 | G5 | | SC | | download |
| Quercus bicolor | Swamp white oak | S1 | G5 | | T | | download |
| Quercus coccinea | Scarlet oak | S1 | G5 | | E | | download |
| Quercus montana | Chestnut oak | S1 | G5 | | T | | download |
| Ranunculus ambigens | Water-plantain spearwort | SH | G4 | | PE | | download |
| Ranunculus fascicularis | Early crowfoot | S1 | G5 | | T | | download |
| Ranunculus gmelinii | Small yellow water crowfoot | S2 | G5T5 | | T | | download |
| Ranunculus lapponicus | Lapland buttercup | S2 | G5 | | T | | download |
| Rhododendron lapponicum | Lapland rosebay | S1 | G5 | | T | | download |
| Rhododendron maximum | Great rhododendron | S1 | G5 | | T | | download |
| Rhododendron viscosum | Clammy azalea | S1 | G5 | | E | | download |
| Rhynchospora capillacea | Horned beak-rush | S1 | G5 | | T | | download |
| Rhynchospora macrostachya | Tall beak-rush | S1 | G4 | | E | | download |
| Rosa acicularis ssp. sayi | Prickly Rose | SH | G5T5 | | PE | | |
| Sagittaria calycina | Spongy arrow-head | S3 | G5T4 | | SC | | download |
| Sagittaria filiformis | Narrow-leaf arrowhead | S2 | G4G5 | | SC | | download |
| Sagittaria rigida | Stiff arrow-head | S2 | G5 | | T | | download |
| Salicornia bigelovii | Dwarf glasswort | S1 | G5 | | SC | | download |
| Salicornia maritima | Jointed Glasswort | SH | G5 | | PE | | |
| Salix arctophila | Arctic willow | S1 | G5 | | E | | download |
| Salix argyrocarpa | Silverleaf willow | SH | G4 | | PE | | download |
| Salix candida | Hoary willow | S1 | G5 | | E | | download |
| Salix herbacea | Dwarf willow | S1 | G5 | | T | | download |
| Salix humilus var. tristis | Dwarf Prairie Willow | SU | G5T5T4 | | SC | | |
| Salix interior | Sandbar willow | S1 | G5 | | E | | download |
| Salix myricoides | Blue-leaf willow | S2 | G4 | | T | | download |
| Salix planifolia | Tea-leaved willow | S1 | G5 | | T | | download |
| Salix uva-ursi | Bearberry willow | S1 | G5 | | T | | download |
| Samolus valerandi | Water pimpernel | S3 | G5T5 | | SC | | download |
| Sanguisorba canadensis | Canada burnet | S1 | G5 | | T | | download |
| Sassafras albidum | Sassafras | S2 | G5 | | SC | | download |
| Saxifraga foliolosa | Star saxifrage | S1 | G4 | | E | | download |
| Saxifraga paniculata | Livelong saxifrage | S1 | G5 | | SC | | download |
| Saxifraga pensylvanica | Swamp saxifrage | S3 | G5 | | SC | | download |
| Scirpus georgianus | Georgia Bulrush | SU | G5 | | SC | | |
| Scirpus longii | Long's bulrush | S2 | G2G3 | | T | | download |
| Scirpus pendulus | Pendulous bulrush | S2 | G5 | | T | | download |
| Scrophularia marilandica | Carpenter's square | SX | G5 | | PE | | |
| Scutellaria parvula | Leonard's skullcap | SH | G4T4 | | PE | | download |
| Selaginella apoda | Creeping spike-moss | S2 | G5 | | E | | download |
| Selaginella selaginoides | Low spike-moss | S1 | G5 | | T | | download |
| Sericocarpus asteroides | White-topped aster | S1 | G5 | | E | | download |
| Shepherdia canadensis | Canada buffaloberry | S1 | G5 | | E | | download |
| Silene acaulis | Moss campion | SX | G5T5 | | PE | | |
| Solidago multiradiata | Cutler's goldenrod | S1 | G5T4 | | T | | download |
| Sorghastrum nutans | Indian grass | S1 | G5 | | E | | download |
| Sphenopholis obtusata | Prairie wedge-grass | SH | G5 | | PE | | |
| Spiraea septentrionalis | Northern meadow-sweet | S1 | G2G3Q | | SC | | download |
| Spiranthes lacera var gracilis | Southern slender ladies' tresses | SH | G5T4T5 | | PE | | |
| Spiranthes lucida | Shining ladies'-tresses | S1 | G5 | | T | | download |
| Sporobolus compositus var. drummondii | Tall dropseed | S1 | G5TNR | | E | | |
| Stuckenia filiformis ssp alpinus | Northern slender pondweed | S1 | G5T5 | | T | | download |
| Stuckenia filiformis ssp occidentalis | Slender pondweed | S1 | G5T5 | | E | | download |
| Suaeda calceoliformis | American sea-blite | S2 | G5 | | T | | download |
| Symphyotrichum anticostense | Anticosti aster | S1 | G3 | | E | | download |
| Symphyotrichum dumosum | Bushy aster | SH | G5T3T5 | | PE | | |
| Symphyotrichum patens | Late purple aster | SX | G5 | | PE | | |
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