Pyrrolizidine alkaloids. There's livertoxic ones, and there's benign ones.
Henriette's herbal blog: The myth that comfrey is completely benign just won't die.
Herbal articles: Pyrrolizidine alkaloids.
Medicinal herbfaq: single herbs.
Henriette's herbal blog: They're cousins of both flavonoids and humanoids.
Henriette's herbal blog: "Coltsfoot" includes both Tussilago and the various species of Petasites.
Henriette's herbal blog: I've avoided plants with livertoxic PAs for years.
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Plant Healer Magazine: Very relevant to the practitioner.
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