Sequoiadendron giganteum
Wellingtonia
Serratula tinctoria
Saw-wort
Sibthorpia europaea
Cornish Moneywort
Silaum silaus
Pepper-saxifrage
Silene acaulis
Moss Campion
Silene armeria
Sweet-William Catchfly
Silene dioica
Red Campion
Silene flos-cuculi
Ragged-Robin
Silene latifolia
White Campion
Silene noctiflora
Night-flowering Catchfly
Silene nutans
Nottingham Catchfly
Silene viscaria
Sticky Catchfly
Silene vulgaris
Bladder Campion
Simethis mattiazzii
Kerry Lily
Sinapis arvensis
Charlock
Sison amomum
Stone Parsley
Sisyrinchium bermudiana
Blue-eyed-grass
Smyrnium perfoliatum
Perfoliate Alexanders
Solanum chenopodioides
Tall Nightshade
Solanum dulcamara
Bittersweet
Solidago canadensis
Canadian Goldenrod
Solidago gigantea
Early Goldenrod
Solidago virgaurea
Goldenrod
Sonchus arvensis
Perennial Sow-thistle