'' Echium plantagineum '' contains pyrrolizidine alkaloids and is poisonous . When eaten in large quantities , it causes reduced livestock weight and death , in severe cases , due to liver damage . Paterson 's curse can also kill horses , and irritate the udders of dairy cows and the skin of humans . After the 2003 Canberra bushfires , a large bloom of the plant occurred on the burned land , and many horses became ill and died from grazing on it . Because the alkaloids can also be found in the nectar of Paterson 's curse , the honey made from it should be blended with other honeys to dilute the toxins
2003 Canberra bushfires
2003 Canberra bushfires
Echium plantagineum