Setaria verticillata
Hooked Bristlegrass
Sibthorpia europaea
Cornish Moneywort
Sida acuta
Common Wireweed
Sida cordata
Long-stalk Sida
Sida rhombifolia
Arrowleaf Sida
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
Solandra grandiflora
Showy Chalicevine
Solanum aethiopicum
Ethiopian Eggplant
Solanum chenopodioides
Tall Nightshade
Solanum dulcamara
Bittersweet
Solanum torvum
Pendejera
Solidago canadensis
Canadian Goldenrod
Solidago gigantea
Early Goldenrod
Solidago virgaurea
Goldenrod
Sonchus arvensis
Perennial Sow-thistle
Sonchus asper
Prickly Sow-thistle
Sonchus oleraceus
Smooth Sow-thistle
Sonneratia caseolaris
Mangrove Apple
Sorbus anglica
English Whitebeam
Sorbus aria
Common Whitebeam
Sorbus aucuparia
Rowan
Sorbus cambrensis
Welsh Whitebeam
Sorbus latifolia
Broad-leaved Whitebeam
Sorbus leyana
Ley's Whitebeam
Sorbus minima
Least Whitebeam
Sorbus mougeotii
Vosges Whitebeam
Sorbus porrigentiformis
Grey-leaved Whitebeam
Sorbus rupicola
Rock Whitebeam
Sorbus stenophylla
Llanthony Whitebeam
Sorbus torminalis
Wild Service-tree
Sorbus x motleyi
Sparganium angustifolium
Floating Bur-reed
Sparganium natans
Least Bur-reed
Spathiphyllum blandum
Pleasant Peace Lily
Spathodea campanulata
African Tulip Tree
Spergula arvensis
Corn Spurrey
Spergularia media
Greater Sea-spurrey
Spergularia rubra
Sand Spurrey
Spergularia rupicola
Rock Sea-spurrey
Spermacoce exilis
False Buttonweed
Spermacoce hispida
Shaggy Buttonweed
Spigelia anthelmia
West Indian Pinkroot
Spiraea canescens
Himalayan Spiraea
Spiraea x rosalba
Intermediate Bridewort
Spiranthes spiralis
Autumn Lady's-tresses
Spirodela polyrhiza
Greater Duckweed
Stachys byzantina
Lamb's-ear
Stachys germanica
Downy Woundwort
Stachys palustris
Marsh Woundwort
Stachys sylvatica
Hedge Woundwort
Staphylea pinnata
Bladdernut
Stellaria alsine
Bog Stitchwort
Stellaria aquatica
Water Chickweed
Stellaria neglecta
Greater Chickweed
Stellaria nemorum
Wood Stitchwort
Streptocarpus ionanthus
African Violet