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Weed Identification

Virginia Tech College of Agriculture and Life Science Virginia Cooperative Extension

Jerusalem artichoke

Family

Asteraceae

Scientific Name

Helianthus tuberosus
Weed photograph 1
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Weed photograph 7
Weed photograph 8

Other Common Names:

Jerusalem sunflower
girasole

Synonyms (former Scientific Names):

Helianthus tomentosus

Habit

A tall (1-3 m) rhizomatous and tuberous perennial. On occasion it is farmed for its edible tubers, but once firmly rooted is competitive and hard to control. Stems are coarse and stout with rough hairs. Plant parts that are above ground die back after frost and do not persevere. Plant over-winters as a tuber. Jerusalem artichoke is a weed of orchards, nurseries, landscapes, and decreased tillage agronomic crops, along with roadsides and waste places. It is frequently discovered on rich, moist soil.

Leaves

Seedling: Cotyledons are oval, twice as long as wide, and united at the base, forming a short tube. The initial leaves are opposite and elliptic. Blades are covered with short stiff hairs, dull green on the upper surface, and pale on the underside. Mature Plant: Leaves are simple, ovate or almost heart-shaped to oblong-lanceolate, tapering to a narrow tip, 10-25 cm long by 4-12 cm wide. Leaf blades are thick, rough on the upper surface, with short grayish hairs on the lower surface. Margins are coarsely toothed, and petioles are winged. Lower leaves are opposite, but leaves on the upper half to two-thirds of the stem are alternate.

Identifying Characteristics

Jerusalem artichoke is occasionally farmed for its edible tubers.

Flower Seed Head

One to five flower heads are produced at the terminal end of stems from August through October. Heads are about 5 cm in diameter with 10-20 yellow ray flowers (2-4 cm long) enveloping the darker yellow disk flowers. Each seed is enclosed within the fruit (achene), which is flattened, 4-8 mm long, and oblong to wedge-shaped.

Seed Fruit

Reproduction is primarily done by tubers but also by seed. Short rhizomes bear tubers at their tips. Tubers are irregularly oval, with knobs or bumps on the surface, reddish on the outside, with white inside. A single plant can make over 200 tubers in a growing season. Tubers created in the previous year begin to sprout in late spring. Tuber reserves are at their lowest in late June (60-70 days after initial shoot surfacing). Rhizome production starts right before flowering. Tuber production starts in midsummer and achieves its peak in late summer to early autumn. The plant tubers can be spread by farming. Dormant tubers are short-lived; they do not survive for more than one or two seasons. As a result, long-term control may be gained by putting a stop to new tuber formation for 2 years.

Where Found

Jerusalem artichoke is continuing to spread in the eastern half of the United States and is multiplying in many areas of the mid-western states and states neighboring Canada. It is also found near the Pacific Coast.

Growth Habit

upright and nonwoody

Thorns or Spines

not present

Approximate Flower Diameter

Varies: 
dime, 
nickle, 
quarter, 
half dollar

Dominant Flower Color

yellow

Flower Symmetry

bilateral symmetry

Leaf Hairs

has hairs

Leaf Arrangement

Varies: 
alternate, 
opposite

Leaf Margin

Varies: 
entire, 
serrated

Leaf Structure

simple

Leaf Stalk

shorter than leaf

Stem Hairs

has hairs

Stem Cross Section

round or oval

Milky Sap

not present

Root Structure

taproot

Life Cycle

perennial

Ochrea

not present

Plant Type

Herb