Silene nutans
Nottingham Catchfly
Silene viscaria
Sticky Catchfly
Silene vulgaris
Bladder Campion
Sinapis alba
White Mustard
Sisymbrium officinale
Hedge Mustard
Smyrnium perfoliatum
Perfoliate Alexanders
Solanum chenopodioides
Tall Nightshade
Solanum dulcamara
Bittersweet
Soleirolia soleirolii
Mind-your-own-business
Solidago canadensis
Canadian Goldenrod
Solidago virgaurea
Goldenrod
Sonchus arvensis
Perennial Sow-thistle
Sonchus asper
Prickly Sow-thistle
Sorbus aria
Common Whitebeam
Sorbus torminalis
Wild Service-tree
Sparganium erectum
Branched Bur-reed
Sparganium natans
Least Bur-reed
Spergula arvensis
Corn Spurrey
Spergularia rubra
Sand Spurrey
Spergularia rupicola
Rock Sea-spurrey
Spiraea x rosalba
Intermediate Bridewort
Spiranthes romanzoffiana
Irish Lady's-tresses
Spiranthes spiralis
Autumn Lady's-tresses
Stachys alpina
Limestone Woundwort