Achillea smithii Hayek accepted as Aspilia floribunda (Gardner) Baker (original description)
Carduus thracicus (Velen.) Hayek (original description)
Carduus vranjanus Adamović ex Hayek (original description)
Centaurea candelabrum Hayek & Košanin accepted as Centaurea melanocephala Pančić (original description)
Centaurea korthiaca Adamović ex Hayek (original description)
Centaurea leucomelaena Hayek (original description)
Centaurea ptarmicifolia Halácsy ex Hayek accepted as Centaurea ptarmicoides Halácsy (original description)
Centaurea thasia Hayek (original description)
Centaurea thracica (Janka) Hayek accepted as Centaurea thracica (Janka) Janka ex Gugler (original description)
Centaurea tubiformis Halácsy ex Hayek (original description)
Centaurea vranjana Adamović ex Hayek (original description)
Cicerbita orbelica (Velen.) Hayek accepted as Lactuca plumieri (L.) Gren. & Godr. (original description)
Cirsium boissieri strib. ex Hayek (original description)
Echinops dumosus Pančić ex Hayek accepted as Echinops microcephalus Sm. (original description)
Erigeron rhodopaeus (Vierh.) Hayek accepted as Erigeron alpinus subsp. rhodopaeus (Vierh.) Kožuharov & N.Andreev (original description)
Hieracium stefanoffii Zahn (original description)
Mycelis glandulosa (Boiss.) Hayek accepted as Lactuca hispida DC. (original description)
Mycelis hispida Hayek accepted as Lactuca hispida DC. (original description)
Tripleurospermum conoclinium (Boiss. & Balansa) Hayek (original description)
Tripleurospermum rosellum (Boiss. & Orph.) Hayek (original description)
Tripleurospermum tempskyanum (Freyn & Sint.) Hayek (original description)