Claim: Rubia cordifolia is a species of flowering plant with roots can be over 1 m long, up to 12 mm thick and it prefers loamy soils with a constant level of moisture.
Evidence: Rubia cordifolia, often known as common madder or Indian madder, is a species of flowering plant in the coffee family, Rubiaceae. The roots can be over 1 m long, up to 12 mm thick. It prefers loamy soils with a constant level of moisture.