• Spiraea salicifolia Bridewort
  
• Spiranthes romanzoffiana Irish Lady's-tresses
  
• Spiranthes spiralis Autumn Lady's-tresses
  
• Spirodela polyrhiza Duckweed, Greater
  
• Stachys palustris Marsh Woundwort
  
• Stachys sylvatica Hedge Woundwort
  
• Stellaria graminea Lesser Stichwort
  
• Stellaria holostea Stichwort, Greater
  
• Stellaria media Common Chickweed
  
• Stellaria uliginosa Bog Stichwort
  
• Suaeda maritima Sea Blite
  
• Succisa pratensis Scabious, Devil's-bit
  
• Symphytum officinale Common Comfrey
  
• Tamus communis Black Bryony
  
• Tanacetum vulgare Tansy
  
• Taraxacum 1 Dandelion
  
• Taraxacum 2 Dandelion
  
• Taraxacum 3 Dandelion
  
• Taraxacum 4 Dandelion
  
• Taraxacum 5 Dandelion
  
• Taraxacum 6 Dandelion
  
• Taraxacum 7 Dandelion
  
• Teucrium scordium Water Germander
  
• Teucrium scorodonia Wood Sage
  
• Thalictrum alpinum Alpine Meadow-rue
  
• Thalictrum flavum Meadow-rue, Common
  
• Thalictrum minus Lesser Meadow-rue
  
• Thlaspi arvense Field Penny-cress
  
• Thymus polytrichus Wild Thyme
  
• Torilis japonica Hedge-parsley, Upright
  
• Torilis nodosa Hedge-parsley, Knotted
  
• Tragopogon pratensis Goat's Beard
  
• Trifolium campestre Hop Trefoil
  
• Trifolium dubium Lesser Trefoil
  
• Trifolium fragiferum Clover, Strawberry
  
• Trifolium hybridum Alsike Clover
  
• Trifolium pratense Red Clover
  
• Trifolium repens White Clover
  
• Triglochin maritima Sea Arrowgrass
  
• Triglochin palustris Marsh Arrowgrass
  
• Tripleurospermum inodorum Scented Mayweed
  
• Tripleurospermum maritimum Sea Mayweed
  
• Tussilago farfara Colt's foot
  
• Typha angustifolia Lesser Bulrush
  
• Typha latifolia Bulrush
  
• Ulex europaeus Gorse
  
• Ulex gallii Western Gorse
  
• Ulmus glabra Wych Elm
  
• Umbilicus rupestris Pennywort
  
• Urtica dioica Nettle, Common