| Sagina apetala | Caryophyllaceae | scheda |
| Sagina maritima | Caryophyllaceae | – |
| Sagina micropetala | Caryophyllaceae | – |
| Sagina procumbens | Caryophyllaceae | scheda |
| Sagina saginoides | Caryophyllaceae | – |
| Sagittaria latifolia | Alismataceae | – |
| Sagittaria sagittifolia | Alismataceae | – |
| Salicornia dolichostachya | Amaranthaceae | – |
| Salicornia patula | Amaranthaceae | – |
| Salicornia veneta | Amaranthaceae | – |
| Salix ×salamonii | Salicaceae | – |
| Salix alba | Salicaceae | scheda |
| Salix alpina | Salicaceae | – |
| Salix apennina | Salicaceae | scheda |
| Salix appendiculata | Salicaceae | scheda |
| Salix aurita | Salicaceae | – |
| Salix breviserrata | Salicaceae | – |
| Salix caesia | Salicaceae | – |
| Salix caprea | Salicaceae | scheda |
| Salix cinerea | Salicaceae | scheda |
| Salix daphnoides | Salicaceae | – |
| Salix eleagnos | Salicaceae | scheda |
| Salix foetida | Salicaceae | – |
| Salix fragilis | Salicaceae | – |
| Salix glabra | Salicaceae | scheda |
| Salix glaucosericea | Salicaceae | – |
| Salix hastata | Salicaceae | – |
| Salix helvetica | Salicaceae | – |
| Salix herbacea | Salicaceae | – |
| Salix mielichhoferi | Salicaceae | – |
| Salix myrsinifolia | Salicaceae | – |
| Salix pentandra | Salicaceae | – |
| Salix purpurea | Salicaceae | scheda |
| Salix reticulata | Salicaceae | scheda |
| Salix retusa | Salicaceae | scheda |
| Salix rosmarinifolia | Salicaceae | – |
| Salix serpyllifolia | Salicaceae | scheda |
| Salix triandra | Salicaceae | scheda |
| Salix viminalis | Salicaceae | – |
| Salix waldsteiniana | Salicaceae | scheda |
| Salsola soda | Amaranthaceae | – |
| Salsola tragus | Amaranthaceae | – |
| Salvia glutinosa | Lamiaceae | scheda |
| Salvia pratensis subsp. pratensis | Lamiaceae | scheda |
| Salvia pratensis subsp. saccardiana | Lamiaceae | – |
| Salvia sclarea | Lamiaceae | scheda |
| Salvia verbenaca | Lamiaceae | scheda |
| Salvia verticillata | Lamiaceae | – |
| Salvinia natans | Salviniaceae | – |
| Samolus valerandi | Primulaceae | scheda |
| Sambucus ebulus | Adoxaceae | scheda |
| Sambucus nigra | Adoxaceae | scheda |
| Sambucus racemosa | Adoxaceae | scheda |
| Sanguisorba minor | Rosaceae | scheda |
| Sanguisorba officinalis | Rosaceae | scheda |
| Sanicula europaea | Apiaceae | scheda |
| Saponaria ocymoides | Caryophyllaceae | scheda |
| Saponaria officinalis | Caryophyllaceae | scheda |
| Saponaria pumila | Caryophyllaceae | – |
| Sarcocornia fruticosa | Amaranthaceae | – |
| Sarcocornia perennis | Amaranthaceae | – |
| Satureja hortensis | Lamiaceae | scheda |
| Satureja montana subsp. variegata | Lamiaceae | scheda |
| Saussurea alpina | Asteraceae | – |
| Saussurea discolor | Asteraceae | – |
| Saxifraga adscendens | Saxifragaceae | – |
| Saxifraga aizoides | Saxifragaceae | scheda |
| Saxifraga androsacea | Saxifragaceae | – |
| Saxifraga aspera | Saxifragaceae | – |
| Saxifraga berica | Saxifragaceae | – |
| Saxifraga biflora | Saxifragaceae | – |
| Saxifraga bryoides | Saxifragaceae | – |
| Saxifraga bulbifera | Saxifragaceae | scheda |
| Saxifraga burseriana | Saxifragaceae | scheda |
| Saxifraga caesia | Saxifragaceae | scheda |
| Saxifraga cernua | Saxifragaceae | – |
| Saxifraga crustata | Saxifragaceae | – |
| Saxifraga cuneifolia subsp. robusta | Saxifragaceae | – |
| Saxifraga depressa | Saxifragaceae | – |
| Saxifraga exarata subsp. moschata | Saxifragaceae | – |
| Saxifraga facchinii | Saxifragaceae | – |
| Saxifraga hostii | Saxifragaceae | scheda |
| Saxifraga mutata | Saxifragaceae | scheda |
| Saxifraga oppositifolia | Saxifragaceae | scheda |
| Saxifraga paniculata | Saxifragaceae | scheda |
| Saxifraga petraea | Saxifragaceae | scheda |
| Saxifraga rotundifolia | Saxifragaceae | scheda |
| Saxifraga sedoides | Saxifragaceae | scheda |
| Saxifraga squarrosa | Saxifragaceae | – |
| Saxifraga stolonifera | Saxifragaceae | – |
| Saxifraga tombeanensis | Saxifragaceae | scheda |
| Saxifraga tridactylites | Saxifragaceae | scheda |
| Scabiosa lucida | Caprifoliaceae | – |
| Scabiosa triandra | Caprifoliaceae | scheda |
| Scabiosa velenovskyana | Caprifoliaceae | scheda |
| Scandix pecten-veneris | Apiaceae | scheda |
| Schedonorus arundinaceus subsp. arundinaceus | Poaceae | scheda |
| Schedonorus arundinaceus subsp. fenas | Poaceae | – |
| Schedonorus giganteus | Poaceae | scheda |
| Schedonorus pratensis subsp. apenninus | Poaceae | – |
| Schedonorus pratensis subsp. pratensis | Poaceae | – |
| Schenkia spicata | Gentianaceae | – |
| Scheuchzeria palustris | Scheuchzeriaceae | – |
| Schlagintweitia intybacea | Asteraceae | – |
| Schoenoplectus carinatus | Cyperaceae | – |
| Schoenoplectus lacustris | Cyperaceae | scheda |
| Schoenoplectus litoralis | Cyperaceae | – |
| Schoenoplectus mucronatus | Cyperaceae | – |
| Schoenoplectus pungens | Cyperaceae | – |
| Schoenoplectus supinus | Cyperaceae | scheda |
| Schoenoplectus tabernaemontani | Cyperaceae | scheda |
| Schoenoplectus triqueter | Cyperaceae | – |
| Schoenus ferrugineus | Cyperaceae | – |
| Schoenus nigricans | Cyperaceae | – |
| Scilla bifolia | Asparagaceae | scheda |
| Scirpoides holoschoenus | Cyperaceae | scheda |
| Scirpoides romanus | Cyperaceae | – |
| Scirpus sylvaticus | Cyperaceae | scheda |
| Scleranthus annuus aggr. | Caryophyllaceae | scheda |
| Scleranthus verticillatus | Caryophyllaceae | – |
| Sclerochloa dura | Poaceae | scheda |
| Scolymus hispanicus | Asteraceae | – |
| Scorpiurus subvillosus | Fabaceae | – |
| Scorzonera aristata | Asteraceae | – |
| Scorzonera austriaca | Asteraceae | scheda |
| Scorzonera hirsuta | Asteraceae | – |
| Scorzonera hispanica | Asteraceae | – |
| Scorzonera humilis | Asteraceae | – |
| Scorzoneroides autumnalis | Asteraceae | – |
| Scorzoneroides helvetica | Asteraceae | – |
| Scorzoneroides montana subsp. melanotricha | Asteraceae | – |
| Scrophularia canina | Scrophulariaceae | scheda |
| Scrophularia juratensis | Scrophulariaceae | scheda |
| Scrophularia nodosa | Scrophulariaceae | scheda |
| Scrophularia umbrosa | Scrophulariaceae | scheda |
| Scrophularia vernalis | Scrophulariaceae | scheda |
| Scutellaria alpina | Lamiaceae | – |
| Scutellaria altissima | Lamiaceae | – |
| Scutellaria galericulata | Lamiaceae | scheda |
| Scutellaria hastifolia | Lamiaceae | – |
| Secale cereale | Poaceae | – |
| Sechium edule | Cucurbitaceae | – |
| Securigera varia | Fabaceae | scheda |
| Sedum acre | Crassulaceae | scheda |
| Sedum album | Crassulaceae | scheda |
| Sedum alpestre | Crassulaceae | – |
| Sedum annuum | Crassulaceae | – |
| Sedum atratum | Crassulaceae | scheda |
| Sedum cepaea | Crassulaceae | – |
| Sedum dasyphyllum | Crassulaceae | scheda |
| Sedum hispanicum | Crassulaceae | scheda |
| Sedum palmeri | Crassulaceae | scheda |
| Sedum rubens | Crassulaceae | scheda |
| Sedum rupestre aggr. | Crassulaceae | scheda |
| Sedum sarmentosum | Crassulaceae | scheda |
| Sedum sexangulare | Crassulaceae | scheda |
| Selaginella helvetica | Selaginellaceae | – |
| Selaginella kraussiana | Selaginellaceae | – |
| Selaginella selaginoides | Selaginellaceae | scheda |
| Selinum carvifolia | Apiaceae | – |
| Sempervivum arachnoideum | Crassulaceae | scheda |
| Sempervivum dolomiticum | Crassulaceae | – |
| Sempervivum montanum | Crassulaceae | – |
| Sempervivum tectorum | Crassulaceae | scheda |
| Sempervivum wulfenii | Crassulaceae | – |
| Senecio cacaliaster | Asteraceae | scheda |
| Senecio doronicum | Asteraceae | scheda |
| Senecio fontanicola | Asteraceae | – |
| Senecio inaequidens | Asteraceae | scheda |
| Senecio nemorensis subsp. glabratus | Asteraceae | – |
| Senecio ovatus | Asteraceae | scheda |
| Senecio squalidus subsp. rupestris | Asteraceae | scheda |
| Senecio sylvaticus | Asteraceae | – |
| Senecio viscosus | Asteraceae | – |
| Senecio vulgaris | Asteraceae | scheda |
| Serapias vomeracea | Orchidaceae | scheda |
| Serratula tinctoria subsp. macrocephala | Asteraceae | scheda |
| Serratula tinctoria subsp. tinctoria | Asteraceae | scheda |
| Seseli annuum | Apiaceae | scheda |
| Seseli kochii | Apiaceae | – |
| Seseli libanotis | Apiaceae | – |
| Seseli pallasii | Apiaceae | scheda |
| Sesleria autumnalis | Poaceae | – |
| Sesleria caerulea | Poaceae | scheda |
| Sesleriella sphaerocephala | Poaceae | scheda |
| Setaria faberi | Poaceae | scheda |
| Setaria italica subsp. italica | Poaceae | scheda |
| Setaria italica subsp. pycnocoma | Poaceae | scheda |
| Setaria italica subsp. viridis | Poaceae | scheda |
| Setaria pumila | Poaceae | scheda |
| Setaria verticillata | Poaceae | scheda |
| Sherardia arvensis | Rubiaceae | scheda |
| Sibbaldia procumbens | Rosaceae | – |
| Sicyos angulatus | Cucurbitaceae | scheda |
| Sida spinosa | Malvaceae | – |
| Sideritis montana | Lamiaceae | – |
| Sigesbeckia orientalis | Asteraceae | – |
| Silene acaulis | Caryophyllaceae | scheda |
| Silene colorata | Caryophyllaceae | – |
| Silene conica | Caryophyllaceae | scheda |
| Silene dioica | Caryophyllaceae | scheda |
| Silene gallica | Caryophyllaceae | scheda |
| Silene latifolia | Caryophyllaceae | scheda |
| Silene nemoralis | Caryophyllaceae | scheda |
| Silene noctiflora | Caryophyllaceae | – |
| Silene nutans | Caryophyllaceae | scheda |
| Silene otites | Caryophyllaceae | scheda |
| Silene saxifraga | Caryophyllaceae | scheda |
| Silene viridiflora | Caryophyllaceae | – |
| Silene vulgaris subsp. commutata | Caryophyllaceae | – |
| Silene vulgaris subsp. glareosa | Caryophyllaceae | scheda |
| Silene vulgaris subsp. vulgaris | Caryophyllaceae | scheda |
| Silphium perfoliatum | Asteraceae | – |
| Silybum marianum | Asteraceae | scheda |
| Sinapis alba | Brassicaceae | scheda |
| Sinapis arvensis | Brassicaceae | scheda |
| Sison amomum | Apiaceae | – |
| Sisymbrium altissimum | Brassicaceae | – |
| Sisymbrium austriacum | Brassicaceae | – |
| Sisymbrium irio | Brassicaceae | scheda |
| Sisymbrium loeselii | Brassicaceae | – |
| Sisymbrium officinale | Brassicaceae | scheda |
| Sisymbrium orientale | Brassicaceae | scheda |
| Sisymbrium strictissimum | Brassicaceae | scheda |
| Sisyrinchium montanum | Iridaceae | – |
| Sium latifolium | Apiaceae | – |
| Smilax aspera | Smilacaceae | – |
| Smyrnium olusatrum | Apiaceae | scheda |
| Smyrnium perfoliatum | Apiaceae | – |
| Solanum carolinense | Solanaceae | scheda |
| Solanum chenopodioides | Solanaceae | scheda |
| Solanum dulcamara | Solanaceae | scheda |
| Solanum lycopersicum | Solanaceae | scheda |
| Solanum melongena | Solanaceae | – |
| Solanum nigrum | Solanaceae | scheda |
| Solanum physalifolium | Solanaceae | – |
| Solanum pseudocapsicum | Solanaceae | scheda |
| Solanum tuberosum | Solanaceae | – |
| Solanum villosum subsp. alatum | Solanaceae | scheda |
| Solanum villosum subsp. villosum | Solanaceae | scheda |
| Soldanella alpina | Primulaceae | scheda |
| Soldanella minima | Primulaceae | scheda |
| Soldanella pusilla subsp. alpicola | Primulaceae | – |
| Soleirolia soleirolii | Urticaceae | scheda |
| Solidago canadensis | Asteraceae | scheda |
| Solidago gigantea | Asteraceae | scheda |
| Solidago virgaurea subsp. minuta | Asteraceae | – |
| Solidago virgaurea subsp. virgaurea | Asteraceae | scheda |
| Sonchus arvensis subsp. arvensis | Asteraceae | scheda |
| Sonchus arvensis subsp. uliginosus | Asteraceae | – |
| Sonchus asper | Asteraceae | scheda |
| Sonchus maritimus | Asteraceae | – |
| Sonchus oleraceus | Asteraceae | scheda |
| Sonchus tenerrimus | Asteraceae | – |
| Sorbaria tomentosa | Rosaceae | – |
| Sorbus aria | Rosaceae | scheda |
| Sorbus aucuparia | Rosaceae | scheda |
| Sorbus austriaca | Rosaceae | – |
| Sorbus chamaemespilus | Rosaceae | scheda |
| Sorbus domestica | Rosaceae | scheda |
| Sorbus torminalis | Rosaceae | scheda |
| Sorghum bicolor | Poaceae | – |
| Sorghum halepense | Poaceae | scheda |
| Sparganium angustifolium | Typhaceae | – |
| Sparganium emersum | Typhaceae | – |
| Sparganium erectum | Typhaceae | scheda |
| Sparganium natans | Typhaceae | – |
| Spartina anglica | Poaceae | – |
| Spartina juncea | Poaceae | – |
| Spartina maritima | Poaceae | – |
| Spartium junceum | Fabaceae | scheda |
| Spergula arvensis | Caryophyllaceae | – |
| Spergularia bocconei | Caryophyllaceae | – |
| Spergularia marina | Caryophyllaceae | – |
| Spergularia media | Caryophyllaceae | – |
| Spergularia rubra | Caryophyllaceae | scheda |
| Spiraea ×vanhouttei | Rosaceae | – |
| Spiraea cantoniensis | Rosaceae | – |
| Spiraea decumbens subsp. tomentosa | Rosaceae | – |
| Spiraea japonica | Rosaceae | – |
| Spiranthes aestivalis | Orchidaceae | – |
| Spiranthes spiralis | Orchidaceae | scheda |
| Spirobassia hirsuta | Amaranthaceae | – |
| Spirodela polyrhiza | Araceae | scheda |
| Sporobolus indicus | Poaceae | scheda |
| Sporobolus neglectus | Poaceae | – |
| Sporobolus vaginiflorus | Poaceae | scheda |
| Stachys alopecuros | Lamiaceae | scheda |
| Stachys alpina | Lamiaceae | scheda |
| Stachys annua | Lamiaceae | scheda |
| Stachys byzantina | Lamiaceae | scheda |
| Stachys germanica | Lamiaceae | scheda |
| Stachys officinalis | Lamiaceae | scheda |
| Stachys palustris | Lamiaceae | scheda |
| Stachys pradica | Lamiaceae | scheda |
| Stachys recta subsp. grandiflora | Lamiaceae | scheda |
| Stachys recta subsp. recta | Lamiaceae | scheda |
| Stachys sylvatica | Lamiaceae | scheda |
| Staphylea pinnata | Staphyleaceae | scheda |
| Stellaria alsine | Caryophyllaceae | – |
| Stellaria aquatica | Caryophyllaceae | scheda |
| Stellaria graminea | Caryophyllaceae | scheda |
| Stellaria holostea | Caryophyllaceae | scheda |
| Stellaria longifolia | Caryophyllaceae | – |
| Stellaria media | Caryophyllaceae | scheda |
| Stellaria neglecta | Caryophyllaceae | scheda |
| Stellaria nemorum subsp. montana | Caryophyllaceae | scheda |
| Stellaria nemorum subsp. nemorum | Caryophyllaceae | scheda |
| Stellaria pallida | Caryophyllaceae | scheda |
| Sternbergia lutea | Amaryllidaceae | scheda |
| Stipa eriocaulis | Poaceae | scheda |
| Stipa feltrina | Poaceae | – |
| Stipa veneta | Poaceae | – |
| Stratiotes aloides | Hydrocharitaceae | – |
| Streptopus amplexifolius | Liliaceae | – |
| Suaeda maritima | Amaranthaceae | – |
| Suaeda vera | Amaranthaceae | – |
| Succisa pratensis | Caprifoliaceae | scheda |
| Succisella inflexa | Caprifoliaceae | – |
| Sulla coronaria | Fabaceae | – |
| Swertia perennis | Gentianaceae | – |
| Symphoricarpos albus | Caprifoliaceae | scheda |
| Symphyotrichum ×salignum | Asteraceae | – |
| Symphyotrichum lanceolatum | Asteraceae | – |
| Symphyotrichum lateriflorum | Asteraceae | – |
| Symphyotrichum novae-angliae | Asteraceae | scheda |
| Symphyotrichum novi-belgii | Asteraceae | scheda |
| Symphyotrichum squamatum | Asteraceae | scheda |
| Symphytum bulbosum | Boraginaceae | scheda |
| Symphytum officinale | Boraginaceae | scheda |
| Symphytum tuberosum subsp. angustifolium | Boraginaceae | scheda |
| Syringa vulgaris | Oleaceae | scheda |