Hemisteptia lyrata 
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