Sharp-lobed Hepatica 
Sharp-lobed Hepatica 
Siberian Larkspur 
Small-fruit pheasant's-eye 
Small-leaved Clematis 
Snake vine 
Snow Buttercup 
Southwestern prickly poppy 
Spanish Poppy 
Squirrel Corn 
Stephania corymbosa 
Stinking Hellebore 
Summer Pheasant's-Eye 
Sweet Autumn Virginsbower 
Syrian Poppy 
Tall anemone 
Thalictrum fendleri 
Thalictrum orientale 
Thalictrum sultanabadense 
Thin Petal Larkspur 
Threeleaf goldthread 
Tiny mousetail 
Twinleaf 
Vancouveria planipetala