Sagina filicaulis
Slender Pearlwort
Sagina nodosa
Knotted Pearlwort
Sagina procumbens
Procumbent Pearlwort
Sagittaria sagittifolia
Arrowhead
Salix aurita
Eared Willow
Salix caprea
Goat Willow
Salix cinerea
Grey Willow
Salix herbacea
Dwarf Willow
Salix pentandra
Bay Willow
Salix repens
Creeping Willow
Salix viminalis
Osier
Salix x fragilis
Crack-willow
Salix x meyeriana
Shiny-leaved Willow
Sambucus ebulus
Dwarf Elder
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
Sisymbrium officinale
Hedge Mustard
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