Sinapis arvensis
Charlock
Sison amomum
Stone Parsley
Sisymbrium officinale
Hedge Mustard
Smyrnium olusatrum
Alexanders
Solanum dulcamara
Bittersweet
Soleirolia soleirolii
Mind-your-own-business
Solidago canadensis
Canadian Goldenrod
Solidago gigantea
Early Goldenrod
Sonchus asper
Prickly Sow-thistle
Sonchus oleraceus
Smooth Sow-thistle
Spergularia marina
Lesser Sea-spurrey
Stachys alpina
Limestone Woundwort
Stachys arvensis
Field Woundwort
Stachys germanica
Downy Woundwort
Stachys sylvatica
Hedge Woundwort
Stellaria media
Common Chickweed
Stellaria neglecta
Greater Chickweed
Symphoricarpos albus
Snowberry
Symphyotrichum lanceolatum
Narrow-leaved Michaelmas-daisy
Symphytum orientale
White Comfrey
Symphytum x uplandicum
Russian Comfrey
Tamus communis
Black Bryony
Tanacetum parthenium
Feverfew
Tanacetum vulgare
Tansy