It seems a reinterpretation of the mistranslation "non-legitimate hellebore" as a common name for the plant Helleborus foetidus, which must have been eleborastro.
ILLEGITIMATE HELLEBORE veratrum viride or false green hellebore is a perennial plant that grows from a small rhizome that throws spectacular leaves. It is extremely toxic by . what is considered as a parasitic plant by farmers