Definition of black root in English:
black root
noun
1Any of various North American medicinal plants with dark-coloured roots; especially a kind of speedwell, Veronicastrum virginicum, native to moist ground in the eastern United States.
2Any of various plant diseases accompanied by a blackening of the roots.
Origin
Early 18th century; earliest use found in William Byrd (1674–1744), landowner and diarist.
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