JMF Invasive Plants Photo Project

Invasive Plants Menu

Herbs

Chinese Yam

Genus/species: Dioscorea polystachya

Description: Chinese Yam is an herbaceous vine that twines counterclockwise as it climbs. Vines grow to about 26 feet. The dense masses of these vines can cover and kill native vegetation, including trees. Identifying characteristics include alternate leaves that are heart shaped (young leaf) to fiddle-shaped (older leaf) with prominent paralleled veins. The rounded stems are thin and wiry. Small white flowers are produced annually. It has winged seeds but the main means of reproduction are potato-like tubers located at the leaf axils and underground tubers. It often has a cinnamon fragrance. With small patches manual control is effective. Herbicide application and repeated treatment usually prevents spread for larger patches.

Garlic Mustard

Genus/species: Alliaria petiolate

Description: Garlic Mustard is a flowering biennial herb that grows up to 4 feet tall in its second year. The first year rosette has heart-shaped coarsely tooth leaves close to the ground which remain green throughout the winter. Identifying characteristics include the flowers which bloom in a cluster at the end of the stem. Each small flower has four white petals and bloom from May to June. The seed capsules are long and become brown as the seeds mature, making it easy to identify. The plant invades from the edge of the forest and then progresses to the interior along streams and trails. Garlic Mustard is not consumed much by our native fauna so it can quickly dominate a site. It is also a serious threat to native butterflies by being toxic to their larvae. To control this plant, hand-pulling and cutting are effective for smaller infestations, but make sure the whole plant is removed and bagged. This plant can mature and produce seeds even if pulled up; so this procedure needs to continue until the seed bank is exhausted (7 years). Larger concentrations can be cut or mowed and this also needs to be done for 7 years. For large infestations, herbicides can be applied to the first year rosettes in the late fall and early spring.

Japanese Knotweed

Genus/species: Polygonum cuspidatum

Description: Japanese Knotweed is an upright shrub-like herbaceous perennial that spreads quickly growing in clumps up to 10 feet tall. Identifying characteristics include heart shape leaves that are 6 inches long and 3 to 4 inches wide and pointed at the tip. It produces very small greenish-white flowers in branched sprays and is followed by small winged fruits. Control is difficult since plants can sprout from very little amounts of root material. All plant parts need to be removed from area. Chemical treatment is used to kill the root system to prevent further sprouting. Multiple follow up treatments are necessary to gain control and eventually eliminate a stand of Japanese Knotweed.

Lesser Celendine

Genus/species: Ranunculus ficaria

Description: Lesser Celandine is a perennial herbaceous flowering plant that completes its life cycle during the winter and spring. By producing large dense patches on the forest floor it displaces the native spring flowering plants. Identifying characteristics include a basal rosette of tender, succulent, shiny, dark green leaves that are kidney to heart shaped. The bright butter-yellow flowers are each on a delicate stalk that rises above the leaves and have from 8 to 12 petals. The flowers open March through April; where large infestations on the forest floor look like a green carpet with yellow dots. Tiny pale-cream colored bulblets are produced in its stem axils and become apparent late in the flowering period. Fingerlike tubers are produced by the roots and are visible when the plant is pulled up. While manual methods are possible for small infestations, the use of systemic herbicide kills the entire plant tip to root and minimizes soil disturbance.

Perrila Mint

Genus/species: Perilla frutescens (L.)

Description: Perilla Mint is an annual herb that grows from 1 to 6.6 feet. Identifying characteristics include square stems covered with short hairs. The leaves are opposite, egg-shape, and green to purple with toothed margins. It produces small, white and purple flowers that are bell-shaped. The flowers are in pairs along the stalk. Perilla Mint has been implicated in cattle poisoning. It readily escapes cultivation and is a problematic invasive plant in natural area by pushing out native plants. Mowing before flowering may reduce its spread.

Poison Hemlock

Genus/species: Conium maculatum

Description: Poison Hemlock is a highly poisonous perennial herbaceous flowering plant and a member of the parsley family growing from 3’ to 8’ tall. The first year is a rosette form and in the second year tall stems and flowers are produced. Identifying characteristics include stout extensively branched, erect smooth green hollow stems with purple spots on the lower portions. The lacey feather-like leaves are large, up to 12” long. Leaflets are shiny green, triangular, and highly dissected. The small white flowers are clustered in an umbrella-like shape 4 to 6 inches across. It produces a large number of seeds that allow the plant to form thick stands. Since the plant is poisonous any part cut or pulled must be bagged and removed from site. Wear protective clothing. A chemical treatment can be used in early spring or late fall.

Pokeweed

Genus/species: Phytolacca Americana

Description: Pokeweed is a large bushy herbaceous perennial flowering herb that can resemble a small tree, growing up to 10 feet in height. It is toxic to humans, pets, and livestock. Identifying characteristics include an enormous white taproot 4 to 6 inches in diameter and large, alternating, smooth, elliptical leaves that are 5 to 20 inches in length. The underside of the leaves, the stems and the veins are pinkish. The flowers have 5 white to pink rounded sepals that are ¼” wide and are in clusters that are 4 to 8 inches long are produced from July to September. The white berries turn dark purple to black and contain black seeds. The seeds can remain viable in the soil for 40 years. To control a few scattered plants, cutting below the root crown is effective. For larger infestations, growing a cultivated crop for 1 to 2 years will help reduce the pokeweed population.