Connecticut Adds Four Plants to its Invasive Plant List
By Peter Russell. Peter Russell is a University of Connecticut Extension Certified Advanced Master Gardener and is the current Chairman of the Board of Directors of the Bartlett Arboretum. In addition to conducting weed and invasive plant identification and control workshops, Peter works with corporations and organizations volunteering on projects on the Arboretum’s 93-acre campus.
This year, the Connecticut state legislature added four species of plants to its invasive plant list based on recommendations from the Invasive Plants Council. The four species added to the list are - Japanese Angelica-tree, Quackgrass, Japanese Wisteria, and Chinese Wisteria. The new law states that “no person shall import, move, sell, purchase, transplant, cultivate or distribute these four plants on or after Oct. 1, 2024.” Below is a brief description and photos of the four new invasive plants.
Japanese Angelica-tree (Aralia elata): The Japanese Angelica-tree is an upright deciduous large shrub or small tree with an irregular, spreading, multi-stemmed form. The bark is rough gray with coarse, thick stems, sharp prickles, and prominent scars left on a stem or twig after the leaf falls off. Leaves are typically dark green although variegated varieties exist. Leaves are compound (pinnate) with leaflets opposite each other and alternate along the stem. Large terminal clusters of tiny white flowers appear in late summer (July-August) followed by small, black fruit.
Quackgrass (Elymus repens): Quackgrass is a cool-season perennial that can survive light frost and return year after year, typically blooming in early spring. It is a sod-forming grass that primarily spreads by rhizomes. A key ID feature of the plant is its clasping auricle (a claw-like appendage at the base of the leaf that wraps around the stem). It has rolled leaves and a short, membranous appendage on the upper side of the leaf (ligule). Lower protective coverings (sheaths) are often hairy while upper sheaths are usually smooth. Leaves are an ashy, blue-green color and sometimes have a longitudinal twist. Quackgrass has also been shown to release chemicals that inhibit the growth of other plants.
Japanese Wisteria (Wisteria floribunda (P)): Japanese Wisteria is a woody deciduous vine that twines clockwise. The stems can twine along a support up to 10 to 25 feet or more or be trained as a shrub or small tree. Bright green compound (pinnate) leaves have 15 to 19 leaflets and 12 to 18-inch long, drooping clusters (racemes) of pink to purple, pea-shaped, fragrant flowers. These flowers bloom from the base of the clusters to the tip as the leaves emerge in spring. After flowering, pendant velvety seed pods, about 6 inches long, ripen in fall. The pods sometimes persist into winter. The vine creates dense thickets by twining and covering over shrubs and trees. The stems root wherever the nodes touch the ground.
References:
· Japanese Angelica-tree: UConn Fact Sheet, Photos by John Hagstrom
· Quackgrass: Purdue University / Photos Aaron J. Patton, and Quincy D. Law
· Japanese Wisteria: North Carolina Extension Gardener / Photos-Leaf Structure Ryan Somma, Twining Vine Scott zona, Form Jim Robbins, Flower David J. Stang)
· Chinese Wisteria: Missouri Botanical Garden description and photos