Schoenoplectus tabernaemontani
Grey Club-rush
Schoenus nigricans
Black Bog-rush
Scilla autumnalis
Autumn Squill
Scilla verna
Spring Squill
Scindapsus pictus
Satin Pothos
Scirpus sylvaticus
Wood Club-rush
Scleranthus annuus
Annual Knawel
Scleranthus perennis
Perennial Knawel
Scrophularia auriculata
Water Figwort
Scrophularia nodosa
Common Figwort
Scutellaria galericulata
Skullcap
Scutellaria minor
Lesser Skullcap
Scutellinia scutellata
Eyelash Cup
Sedum acre
Biting Stonecrop
Sedum album
White Stonecrop
Sedum anglicum
English Stonecrop
Seemannia sylvatica
Bolivian Sunset Gloxinia
Senecio cambrensis
Welsh Groundsel
Senecio inaequidens
Narrow-leaved Ragwort
Senecio sarracenicus
Broad-leaved Ragwort
Senecio squalidus
Oxford Ragwort
Senecio viscosus
Sticky Groundsel
Senna fistula
Golden Shower Tree
Senna obtusifolia
Sicklepod
Sequoiadendron giganteum
Wellingtonia
Serratula tinctoria
Saw-wort
Sherardia arvensis
Field Madder
Sibthorpia europaea
Cornish Moneywort
Sicyos edulis
Chayote
Sida rhombifolia
Arrowleaf Sida
Silaum silaus
Pepper-saxifrage
Silene dioica
Red Campion
Silene flos-cuculi
Ragged-Robin
Silene gallica
Small-flowered Catchfly
Silene noctiflora
Night-flowering Catchfly
Silene nutans
Nottingham Catchfly
Silene uniflora
Sea Campion
Silene viscaria
Sticky Catchfly
Silene vulgaris
Bladder Campion
Simethis mattiazzii
Kerry Lily
Sinapis arvensis
Charlock
Sisyrinchium bermudiana
Blue-eyed-grass
Smyrnium perfoliatum
Perfoliate Alexanders
Solandra grandiflora
Showy Chalicevine
Solanum dulcamara
Bittersweet
Solanum erianthum
Velvet Nightshade
Solanum nigrum
Black Nightshade
Solidago canadensis
Canadian Goldenrod
Solidago gigantea
Early Goldenrod
Solidago virgaurea
Goldenrod
Sonchus arvensis
Perennial Sow-thistle
Sorbus aucuparia
Rowan
Sorbus minima
Least Whitebeam
Sorbus torminalis
Wild Service-tree
Sparganium erectum
Branched Bur-reed
Sparganium natans
Least Bur-reed
Spergula arvensis
Corn Spurrey
Spergularia marina
Lesser Sea-spurrey
Spergularia media
Greater Sea-spurrey
Spergularia rubra
Sand Spurrey
Spergularia rupicola
Rock Sea-spurrey
Sphagneticola trilobata
Bay Biscayne Creeping-oxeye
Spiranthes romanzoffiana
Irish Lady's-tresses
Spiranthes spiralis
Autumn Lady's-tresses
Splachnum ampullaceum
Cruet Collar-moss
Stachys arvensis
Field Woundwort
Stachys germanica
Downy Woundwort
Stachys palustris
Marsh Woundwort
Stachytarpheta jamaicensis
Blue Porterweed
Stapelia variegata