(a.k.a. coypu, swamp beaver)
➚ DESCRIPTION: This annual, which reaches
one to three feet in height, resembles a
miniature bamboo. Light-green, lance-shaped leaves are about three inches in
length. Japanese stilt grass produces airy
flower spikes in late summer and early fall.
➚ ORIGIN: Once used as a packing material
to ship delicate porcelain from the Far
East, Japanese stilt grass made its first
U.S. appearance in Tennessee in 1919.
➚ WATERSHED WHEREABOUTS: Now present
from New York to Florida, Japanese stilt
grass can be found along rivers and
streams and in floodplains, wetlands,
➚ DESCRIPTION: These beaver-like rodents
with long thin tails can weight up to 20
pounds. Nutria have thick brown fur, large
orange front teeth, and webbed feet. The
high placement of their facial features
allows them to swim with little exposed.
➚ ORIGIN: These South American natives
were brought to the Blackwater National
Wildlife Refuge on Maryland’s Eastern
Shore in 1943 for fur farming.
➚ WATERSHED WHEREABOUTS: Fur farm
escapees have established populations in
Maryland, Delaware, and Virginia, including
areas around the Potomac and Patuxent
rivers on the Western Shore.
➚ DESCRIPTION: A member of the ginseng
family, this evergreen vine is a virile ground
cover and climber. Variable leaf forms, the
most popular being three-lobed, are dark
green and waxy.
➚ ORIGIN: It is believed that English ivy was
brought to the U.S. by European settlers
who prized it as a dependable ground
cover. The vine is native to Europe, Western
Asia, and Northern Africa.
➚ WATERSHED WHEREABOUTS: Sold widely
in the U.S. as an ornamental plant, English
ivy is found abundantly throughout the
➚ THREATS: Japanese stilt grass spreads by
rooting along stem joints and by seed.
Each node can produce one new plant
and each plant can produce up to 1,000
seeds. The plant is especially intrusive in
areas where soil is disturbed by mowing,
tilling, deer traffic, and other activities.
Uncontrolled, Japanese stilt grass will
destroy native understory in areas from
full sun to deep shade.