Taxus Baccata - Toxicity

Toxicity

Most parts of the tree are toxic, except the bright red aril surrounding the seed. The foliage remains toxic even when wilted, and toxicity increases in potency when dried. Ingestion and subsequent excretion by birds whose beaks and digestive systems do not break down the seed's coating are the primary means of yew dispersal. The major toxin within the yew is the alkaloid taxine. Horses have the lowest tolerance to taxine, with a lethal dose of 200–400 mg/kg body weight, cattle, pigs, and other livestock are only slightly less vulnerable. Symptoms of yew poisoning include an accelerated heart rate, muscle tremors, convulsions, collapse, difficulty breathing, circulation impairment and eventually heart failure. However, there may be no symptoms, and if poisoning remains undetected death may occur within hours. Fatal poisoning in humans is very rare, usually occurring after consuming yew foliage. The leaves are more toxic than the seed.