Hemp Agrimony 
Heyne's Lobelia 
Hieracium albiflorum 
Hieracium lachenalii 
Hieracium murorum 
Hierba pulguera 
Hoary ragwort 
Hoary Sunray 
Hoary Tansyaster 
Hollow Joe-Pye weed 
Hooker’s thistle 
Hop goodenia 
Hypochaeris setosa 
Iberian knapweed 
Idaho Gumweed 
Illyrian Thistle 
Indian blanketflower 
Indian Globe Thistle 
Indian tobacco 
Inula aschersoniana 
Inula salicifolia 
Iphiona mucronata 
Iphiona scabra 
Iranian Knapweed