Goutweed or Bishop's Weed

Fact Sheet TreatmentAegopodium podagraria

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Common look-alikes:

Identification

Appearance

Aegopodium podagraria is a creeping, herbaceous perennial that can grow to be 15-40 inches tall.

Foliage

The basal and lower leaves have long petioles. There are usually 9 leaflets per lower leaf, although this can vary. Each leaflet is ovate with an acute or acuminate apex. The bases of these leaflets can be rounded or cordate. The lower leaflets are 1-3 inches long and have a serrate margin. The upper leaflets are similar to the lower leaflets, but are smaller and ternate in their arrangement, and have shorter petioles. A commonly planted form has variegated leaves, bluish-green color leaves with creamy white edges.

Flowers

The white flowers are arranged in umbels that are 2.25-4.75 inches in diameter. Each umbel is borne on a long peduncle, and has 15-25 rays that are about 1 inch or more in length. The flowers of Aegopodium podagraria appear in June.

Fruit

The brown fruits oblong-ovoid, laterally flattened and 0.12-0.16 inches long.

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Biology

Ecological Threat

Goutweed is aggressive, forming dense, impenetrable patches that displace native plants and greatly reduce ground-layer species diversity. Its colonies also inhibit the establishment of native tree seedlings. Highly shade tolerant, it is capable of invading closed-canopy forests.

Origin

Goutweed was brought to North America as an ornamental by early European settlers. By 1863, it was well established in the United States. It is utilized as a low maintenance ground cover.

Habitat

Forest, forest edge, riverbank, streambank, meadows, fields, disturbed areas

Life Cycle

Goutweed is an aggressive perennial that reproduces primarily vegetatively through a rhizome system. Seeds require cold stratification to germinate, and the seed bank is short-lived. Seeds usually will germinate the next year after initial dispersal. New foliage appears in early spring and flowers bloom in June with small white umbels. The seeds turn brown when they ripen in late summer.

Management Options

This species is Quarantined: Class B Noxious Weed

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Mechanical Control

Small patches can be eliminated through persistent hand-pulling, careful to remove underground rhizomes. Rhizomes should be bagged and disposed of to prevent reestablishment. Frequent mowing at short heights can control or slow the spread of goutweed. Doing this early in the year just after the plant has fully leafed out, and covering the entire colony with black plastic sheeting afterwards, is a great way to exhaust its energy reserves.

Goutweed may also be cut in late summer, after leaf-out, and then covered with plastic.

DO NOT HOME COMPOST! DO NOT DISCARD IN WOODS OR FIELD!

Plant fragments will re-sprout.

Chemical Control

Systemic herbicides, such as glyphosate, are most effective for goutweed control because they are translocated to the roots, killing the entire plant. Contact herbicides are ineffective because goutweed readily leafs out after defoliation.

Be careful not to damage or kill nearby native plants when conducting management work.
Always read and follow pesticide label directions. Application of pesticides may require a certification from the Agency of Agriculture, Food and Markets. The Agency website provides information on what applicator certification is needed.