Sweet Everlasting 
Sweet Joe-Pye weed 
Symphyotrichum subulatum 
Syrian Cornflower-thistle 
Syrian Wild Artichoke 
Tagetes tenuifolia 
Tahoka Daisy 
Takhtajaniantha 
Tall beggarticks 
Tall blue lettuce 
Tall Elephant's-Foot 
Tall Lettuce 
Tall Rattlesnakeroot 
Tall thistle 
Tanacetum aucheri 
Tanacetum microphyllum 
Tanacetum sinaica 
Tansy 
Tansy ragwort 
Taraxacum cyprium 
Taraxacum syriacum 
Tarlmounia elliptica 
Texas Thistle 
Thinleaf Sunflower