Plant Invaders of Mid-Atlantic Natural Areas - National Park Service

HERBACEOUS FORBS
• Leaves: opposite, heart-shaped with scalloped margins, about an
inch across and have a musky mint odor when crushed.
• Flowers, fruits and seeds: flowers are about ½-¾ in. long, tubular,
lavender, paired and emerge from leaf axils; flowering occurs
March to July; each flower produces a pod containing four smooth
tan seeds.
• Spreads: by vegetatively by creeping stems and to a lesser
degree by seed; shallow fibrous roots form at the base of the plant
and at leaf nodes on the stem.
• Look-alikes: henbit ( Lamium amplexicaule), purple deadnettle
(Lamium purpureum), first-year garlic mustard (Alliaria
petiolata), and possibly other small herbaceous plants with
opposite leaves and blue flowers.
Prevention and Control
Once established, this plant is difficult to control because it is hard to
remove all root and stolon fragments. Seed banks may also remain
viable after control methods are used. Small patches can be pulled
by hand or using a rake when the soil is damp. All roots must be
removed. Large infestations can be effectively controlled using
systemic herbicides like glyphosate (see Control Options). A rust
fungus Puccinia glechomatis attacks ground ivy causing severe
damage or death and may hold some potential for biological control.
Japanese Knotweed _______________________
Fallopia japonica (Hout.) R. Decr.
(previously Polygonum cuspidatum)
Buckwheat family (Lythraceae)
Origin: Eastern Asia
Background
Japanese knotweed was probably
introduced into the United States
in the late 1800s. First used as an
ornamental plant, it has also been
planted for erosion control and
landscape screening. It is designated
a noxious weed in the state of
Washington.
Distribution and Habitat
Japanese knotweed occurs across the U.S. and has been reported to
be invasive in natural areas throughout the northeast into Georgia
and west to Missouri, with additional infestations in Oregon and
Washington. It can tolerate a wide variety of challenging conditions,
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Bill Johnson