Japanese hedge parsley

not listed

NNA - Not applicable

SNA - Not applicable

not listed

Japanese hedge parsley is listed as an invasive terrestrial plant by the Minnesota Department of Natural Resources under the name erect hedge parsley. However, it is not currently regulated in Minnesota. It is listed as Prohibited/Restricted Invasive - Eradicate! in Wisconsin.

Japanese hedge parsley is native to Europe, Asia, and the Indian subcontinent. It was introduced in North America in 1917 and is now naturalized. In the United States it is widespread but sporadic in the east and in the Pacific Northwest. It is found in natural areas, including open woodlands, woodland edges, savannas, and thickets; and in disturbed sites, including pastures, roadsides, and railroads. It grows under partial sun to full shade, sometimes under full sun, in dry to moderately moist soil. It is considered an aggressively invasive weed here, where it can out-compete native species. Wisconsin lists it as Prohibited/Restricted Invasive - Eradicate! (their emphasis). In Minnesota it is not listed but there is a program to eradicate it in Dakota County parks.

Japanese hedge parsley is an erect forb that rises on multiple stems from a thick taproot. It can be 8″ to 48″ tall, but in Minnesota flowering plants are usually no more than 24″ in height. In Minnesota it is a biennial, taking two years to complete its life cycle. In more southerly regions it is an annual.

The stems are green, erect, round, grooved, and branched. They are mostly slender but usually stout near the base. They are rough to the touch and are covered with stiff, white, appressed, downward-pointing hairs.

In the first year only a radiating cluster (rosette) of basal leaves is produced. These leaves rise from the taproot on long, slender stalks (petioles). The petioles are covered with stiff, white, appressed, downward-pointing hairs, and their margins are rolled inward toward the upper side. The basal leaves are usually present at flowering time. The leaf blade is fern-like, triangular in outline, and up to 6″ (15 cm) long. It is pinnately divided into one or two pairs of opposite leaflets and a terminal leaflet. Each leaflet is lance-shaped to oblong egg-shaped, up to 2⅜″ (6 cm) long, and again pinnately divided into 3 or 5 lobes. The ultimate lobes are sharply pointed at the tip. The upper and lower surfaces are moderately to densely covered with stiff white hairs. The margins have a few sharp teeth. The lowest teeth are deeply cut.

Stem leaves are similar to basal leaves. They get progressively smaller, less divided, and shorter stalked as they climb the stem. Lower stem leaves are 2″ to 5″ long, twice pinnate, and on long or short petioles. The base of the petiole surrounds (sheaths) the stem, forming a small cup at the point of attachment. The uppermost stem leaves, just below the inflorescence, are divided into 3 narrowly egg- or lance-shaped leaflets and are short-stalked.

The inflorescence is a loose, compound, umbrella-shaped cluster (umbel) at the end of the stem and each branch, and sometimes from an upper leaf axil. The umbel is round, more or less flat-topped, and up to 2″ in diameter. It is at the end of a 13⁄16″ to 4¾″ (3 to 12 cm) long stalk (peduncle). The peduncle is covered with stiff, appressed, downward-pointing hairs. The umbel has 5 to 10 slender branches (rays) and is subtended by 3 to 10, narrow, straight-sided (linear), modified leaves (bracts). The bracts are unequal in size. The longest is up to ⅝″ long. All are longer than the arms (raylets) of the associated umbellet. All are covered with stiff, appressed, upward-pointing hairs. Each ray is ⅜″to 1¾″ long and is also covered with stiff, appressed, upward-pointing hairs. At the end of each ray is a smaller, secondary umbel (umbellet). Each umbellet has 5 to 20 raylets and is subtended by 1 to 8 narrowly triangular, linear, or hair-like bractlets. The bractlets are about 3⁄16″ (5 mm) long and are covered with stiff, appressed, upward-pointing hairs. Each raylet is about ⅛″ (3 mm) long and is covered with stiff, appressed, upward-pointing hairs. At the end of each raylet there is a single tiny flower.

The flowers are about 3 ⁄16″ (5 mm) wide. Inner flowers of the umbellet are symmetrical on every plane, like a starfish (actinomorphic). Outer flowers are sometimes symmetrical on only one plane (zygomorphic). There are 5 outer floral leaves (sepals), 5 petals, 5 stamens, and 2 styles. The sepals are very small, less than 1⁄64″ (0.5 mm) long. The petals are white, inversely egg-shaped, and deeply notched at the tip. The outer petals of the outer flowers are enlarged, up to 1⁄16″ (2 mm) long, and broad. The stamens are small and have white anthers. The styles are green.

The fruit is an oblong-elliptic to egg-shaped, 1⁄16″ to ⅛″ (2 to 4 mm) long, ⅛″ (3 mm) wide capsule containing 2 seeds. It is whitish green at first, turning dark brown at maturity. It is densely covered with 1⁄64″ to 1⁄32″ (0.4 to 0.8 mm) long hooked hairs that will stubbornly cling to any fabric.

8″ to 48″

White

Spreading hedge parsley (Torilis arvensis) umbels do not have bracts below each umbel.

Dry to moderately moist. Open woodlands, woodland edges, savannas, thickets, pastures, roadsides, and railroads. Full shade to full sun.

June to August

Sources

2, 3, 4, 7, 22, 28, 29, 30.

Native to Europe, Asia, and the Indian subcontinent. Introduced and naturalized in North America.

Widespread and sporadic

Plant

Inflorescence

Leaves

Location: 45819 404th Ave Mazeppa, Wabasha County, MN

We carefully disposed of and bagged dozens of these plants in the last 2 years.