That's American English for you: more roots than a mangrove swamp.
Roy Blount, Jr. (2009). “Alphabet Juice: The Energies, Gists, and Spirits of Letters, Words, and Combinations Thereof; Their Roots, Bones, Innards, Piths, Pips, and Secret Parts, Tinctures, Tonics, and Essences; With Examples of Their Usage Foul and Savory”, p.466, Macmillan
