Silene viscaria
Sticky Catchfly
Silene vulgaris
Bladder Campion
Simethis mattiazzii
Kerry Lily
Sinapis arvensis
Charlock
Sisyrinchium bermudiana
Blue-eyed-grass
Smyrnium perfoliatum
Perfoliate Alexanders
Solanum dulcamara
Bittersweet
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
Spiranthes romanzoffiana
Irish Lady's-tresses
Spiranthes spiralis
Autumn Lady's-tresses