Oriental Bittersweet
Oriental, or Asiatic, bittersweet is a perennial, deciduous vine that can grow to 60 feet. Stems have dark brown, striated bark. Elliptic to ovate leaves are alternate and spiral evenly around the stem. Axillary flowers bloom in May to early June yielding bright, reddish-orange fruit in the fall. Oriental bittersweet can be confused with American bittersweet, which has a terminal inflorescence and is native.
Garlic Mustard
Garlic mustard is a biennial herb and grows as a rosette of kidney shaped leaves in the first year. The second-year plant can grow multiple stems up to four feet with triangular, sharply-toothed leaves. In May, four-petaled, white flowers grow in clusters at the top of the stem. Garlic mustard produces a multitude of seeds, which can remain viable for seven years or more.
Common Reed Grass
Common reed grass, or phragmites, is a tall, herbaceous perennial ranging in height from 3-15 feet. Leaves and stems are stiff and sharp. Large, feathery plumes of flowers change from purple-brown in July, to tan-grey by late in the season.
Japanese Knotweed
Japanese knotweed is a fast-growing, herbaceous perennial with jointed, hollow stems and alternate, leathery leaves that are broadly ovate. A cascade of white flowers blooms in August, and dormant reddish stems are visible in winter. Giant knotweed, Fallopia sachalinensis, is another nonnative knotweed in the Park.
Giant Hogweed
Giant hogweed is a biennial herb that grows to 8-14 feet. Plants sprout in early spring from forked taproots or seeds. Stems are hollow, and leaves are lobed. The best time to identify giant hogweed is when it is in bloom in June.
