Selaginella famairei Selaginella martensii 'Albovariegata'
Selaginella plana Selaginella versicolor
Sempervivum Sempervivum 'Commander Hay'
Sempervivum 'Kalinda' Sempervivum 'Oddity'
Sempervivum 'Pilioseum' Sempervivum 'Purple Beauty'
Sempervivum 'Raspberry Ice' Sempervivum 'Red Beauty'
Sempervivum 'Sanford Hybrids' Sempervivum 'Silverine'
Sempervivum alba Sempervivum arachnoideum
Sempervivum arachnoideum 'Red Cobweb' Sempervivum arachnoideum var. tomentosum
Sempervivum calcareum 'Mrs. Giuseppi' Sempervivum carneum
Sempervivum pomelii Sempervivum pumilum
Sempervivum x roseum 'Fimbriatum' Sempervivum tectorum
Sempervivum tectorum 'Cleveland Morgan' Sempervivum tectorum 'Violaceum'
Senecio barbertonicus Senecio cineraria
Senecio cineraria 'Cirrus' Senecio cineraria 'New Look'
Senecio cineraria 'Silver Lace' Senecio cineraria 'Silverdust'
Senecio cineraria 'Snowstorm' Senecio crassissimus
Senecio doria Senecio hallianus
Senecio mandraliscae Senecio serpens
Senecio viravira Senegalia greggii
Senna alata Senna bicapsularis
Senna candolleana Senna corymbosa
Senna covesii Senna marilandica
Senna nemophila Senna phyllodinea
Senna polyphylla Senna spectabilis
Sequoia sempervirens Sequoia sempervirens 'Emily Brown'
Sequoia sempervirens 'Filoli' Sequoia sempervirens 'Prostrata'
Sequoia sempervirens 'Simpson's Silver' Sequoia sempervirens 'Soquel'
Sequoiadendron giganteum Sequoiadendron giganteum 'Pendula'
Serenoa repens Seriphidium canum
Seriphidium tripartitum Serissa foetida 'Variegata'
Serissa foetida 'White Swan' Seseli gummiferum
Sesleria autumnalis Sesleria caerulea
Setaria faberi Setaria palmifolia
Setaria palmifolia 'Rubra Variegata' Severinia buxifolia
Shepherdia argentea Shepherdia canadensis
Shepherdia rotundifolia Shibataea kumasasa
Shortia galacifolia Sida eggersii
Sidalcea x 'Party Girl' Sidalcea malviflora 'Elsie Heugh'
Sidalcea malviflora 'Little Princess' Silene armeria 'Electra'
Silene dioica 'Clifford Moor' Silene latifolia
Silene mexicana 'Hot Stuff' Silene polypetala
Silene uniflora Silene uniflora 'Druett's Variegated'
Silene uniflora 'Swan Lake' Silene virginica
Silphium gracile Silphium perfoliatum
Silybum marianum Simarouba glauca
Simmondsia chinensis Sinapis arvensis
Sinarundinaria nitida Sinningia sellovii
Sinningia speciosa X Sinocalycanthus raulstonii 'Hartlage Wine'