Assertion: comfrey's effect | /r/HasProperty | gardner
Facets:
Source sentences:
text: Compared to true comfrey (Symphytum officinale), species of comfrey such as Russian comfrey (Symphytum x uplandicum) and prickly comfrey (Symphytum asperum) contain the more toxic macrocyclic diester PAs (Hoffmann, 2003) and higher levels of echimidine, which has exhibited a more toxic effect (Gardner & McGuffin, 2013).