JERUSALEM ARTICHOKE, Helianthus tuberosus L. 1, lower part of stem with roots, rhizomes, and immature tubers; 2, section from middle of stem; 3, upper portion of stem with flower heads. Perennial, reproducing by rhizomes, tubers, and seeds. Roots fibrous, from short rhizomes which bear edible white tubers at tips. Stems erect, usually branching above, rough-hairy, up to 9 feet (2.7 m) high. Leaves simple, large, opposite on lower part and alternate on upper part of stem, upper surface very rough, lower surface hairy, varying from egg-shaped to lance-shaped, edges saw toothed. Flower heads about 2 inches (5 cm) in diameter, with large yellow ray flowers surrounding yellow disk flowers. Seed flattened, wedge-shaped, smooth, often mottled with black. Found in moist fields, fence rows, roadsides, and woods. Troublesome when established in cultivated fields.