Sambucus nigra
Elder
Sanguisorba officinalis
Great Burnet
Sanicula europaea
Sanicle
Saponaria officinalis
Soapwort
Sarcoscypha austriaca
Scarlet Elfcup
Saturnia pavonia
Emperor Moth
Saxifraga granulata
Meadow Saxifrage
Saxifraga hypnoides
Mossy Saxifrage
Saxifraga oppositifolia
Purple Saxifrage
Saxifraga tridactylites
Rue-leaved Saxifrage
Scabiosa columbaria
Small Scabious
Schedonorus giganteus
Giant Fescue
Schoenoplectus lacustris
Common Club-rush
Schoenoplectus tabernaemontani
Grey Club-rush
Scirpus sylvaticus
Wood Club-rush
Scleranthus annuus
Annual Knawel
Scorzoneroides autumnalis
Autumn Hawkbit
Scrophularia auriculata
Water Figwort
Scrophularia nodosa
Common Figwort
Scutellaria galericulata
Skullcap
Scutellaria minor
Lesser Skullcap
Sedum acre
Biting Stonecrop
Sedum album
White Stonecrop
Sedum anglicum
English Stonecrop
Senecio squalidus
Oxford Ragwort
Senecio viscosus
Sticky Groundsel
Senecio vulgaris
Groundsel
Sequoia sempervirens
Coastal Redwood
Sequoiadendron giganteum
Wellingtonia
Serratula tinctoria
Saw-wort
Setaria viridis
Green Bristle-grass
Sherardia arvensis
Field Madder
Sibthorpia europaea
Cornish Moneywort
Silaum silaus
Pepper-saxifrage
Silene dioica
Red Campion
Silene flos-cuculi
Ragged-Robin
Silene gallica
Small-flowered Catchfly
Silene latifolia
White Campion
Silene uniflora
Sea Campion
Sisyrinchium montanum
American Blue-eyed-grass
Smyrnium olusatrum
Alexanders
Solanum dulcamara
Bittersweet
Solanum nigrum
Black Nightshade
Solidago virgaurea
Goldenrod
Sonchus asper
Prickly Sow-thistle
Sorbus aria
Common Whitebeam
Sorbus aucuparia
Rowan
Sorbus cambrensis
Welsh Whitebeam
Sorbus leptophylla
Thin-leaved Whitebeam
Sorbus leyana
Ley's Whitebeam
Sorbus minima
Least Whitebeam
Sorbus porrigentiformis
Grey-leaved Whitebeam
Sorbus stenophylla
Llanthony Whitebeam
Sorbus torminalis
Wild Service-tree
Sparganium angustifolium
Floating Bur-reed
Sparganium erectum
Branched Bur-reed
Sparganium natans
Least Bur-reed
Spergula arvensis
Corn Spurrey
Spergularia rubra
Sand Spurrey
Spiraea x rosalba
Intermediate Bridewort
Spiranthes spiralis
Autumn Lady's-tresses
Stachys arvensis
Field Woundwort
Stachys palustris
Marsh Woundwort
Stachys sylvatica
Hedge Woundwort
Staphylea pinnata
Bladdernut
Stellaria alsine
Bog Stitchwort
Stellaria aquatica
Water Chickweed
Stellaria graminea
Lesser Stitchwort
Stellaria holostea
Greater Stitchwort
Stereum gausapatum
Bleeding Oak Crust