• WordNet 3.6
    • n redroot perennial woodland native of North America having a red root and red sap and bearing a solitary lobed leaf and white flower in early spring and having acrid emetic properties; rootstock used as a stimulant and expectorant
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Webster's Revised Unabridged Dictionary
    • n Redroot (Bot) A name of several plants having red roots, as the New Jersey tea (see under Tea), the gromwell, the bloodroot, and the Lachnanthes tinctoria, an endogenous plant found in sandy swamps from Rhode Island to Florida.
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Century Dictionary and Cyclopedia
    • n redroot An American shrub, Ceanothus Americanus, the New Jersey tea. The stems are from 1 to 3 feet high from a dark-red root, the leaves ovate or oblong-ovate, the small white flowers gathered in rather pretty dense clusters at the ends of leafy shoots. The name is more or less extended to other members of the genus.
    • n redroot A herbaceous plant, Lachnanthes tinctoria, of the Hæmodoraceæ, or bloodwort family. It grows in wet sandy places in the eastern United States near the coast. It has a simple stem with sword-shaped leaves mostly from near the base, and woolly flowers, yellow within, crowded in a dense compound cyme. The root is red, and has been used in dyeing. Upon authority adduced by Darwin (“Origin of Species,” ch. i.), the root of this plant is fatally poisonous to white pigs which eat it, but not to black; the statement, however, requires confirmation. Also paintroot.
    • n redroot The alkanet, Alkanna tinctoria.
    • n redroot One of the pigweeds, Amarantus retroflexus.
    • n redroot The bloodroot, Sanguinaria Canadensis.
    • n redroot The field-gromwell, Lithospermum arvense.
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In literature:

The weeds commonly called redroot or iron-weed are very good for this.
"Games for the Playground, Home, School and Gymnasium" by Jessie H. Bancroft
Old lady Field she make medicine with snakeroot and larkspur and marshroot and redroot.
"Slave Narratives: a Folk History of Slavery in the United States From Interviews with Former Slaves" by Work Projects Administration
It does indeed look like a kind of forethought in the redroot.
"A Year in the Fields" by John Burroughs