Previously, lack of proper termology to report this condition was an issue, often colloquially termed the "black triangle"; angularis nigra was coined at the University of Toronto Faculty of Dentistry.
Sambucus nigra | Centaurea nigra | Pinus nigra | Juglans nigra | Fraxinus nigra | Carex nigra | Brassica nigra | Populus nigra | Tinea nigra | Prosopis nigra | Porta Nigra | ''Populus nigra'', originating in the United States from plantings by André Michaux | M. nigra | Mined leaf of ''Centaurea nigra | Leaf of ''Ballota nigra | Hoplocorypha nigra | Gila nigra | Betula nigra | A shoot of ''Centaurea nigra |