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Polygonum cuspidatum

Polygonum cuspidatum Siebold & Zucc.

Fallopia japonica (Houtt.) Ronse Decr.

Pleuropterus cuspidatus (Siebold & Zucc.) Moldenke

Pleuropterus zuccarinii (Small) Small

Polygonum cuspidatum Siebold & Zucc. var. compactum (Hook. f.) L.H. Bailey

Polygonum zuccarinii Small

Reynoutria japonica Houtt.

Japanese Knotweed, Mexican Bamboo

KingdomPlantaePlants, but not fungi, lichens, or algae
SubkingdomTracheobiontaVascular plants—plants with a “circulatory system” for delivering water and nutrients
DivisionMagnoliophytaFlowering plants, also known as angiosperms
ClassMagnoliopsidaDicotyledons—plants with two initial seed leaves
SubclassCaryophyllidaeCacti, many other succulents, carnivorous plants, and leadworts
OrderCaryophyllalesIncludes cacti, carnations, amaranths, ice plants, and many carnivorous plants
FamilyPolygonaceaeKnotweed or smartweed family
GenusPolygonumGreek poly, “many,” and gonu, “knee,” for the swollen jointed stems
Speciescuspidatum“Tipped with a firm point”

About plant names...

Another story of a good plant gone bad. Japanese knotweed is a native of Japan, China, and Korea. Introduced to Europe and North America as an ornamental plant, it has been so successful that it is considered one of the 100 worst invasive species. Fast-growing root systems form dense hedges that crowd out other species.

Identification: Japanese knotweed stems are jointed and hollow like bamboo. Thin branches are reddish. Plants reach up to 12' (3.7 m). Flowers appear in multiple upward pointing spikes containing many tiny white to pale yellow flowers. Leaves are oval, wider near the base, 2-6" (5-15 cm) long and 1-4" (2.5-10 cm) wide. Seed pods are shaped like inverted hearts, about ⅛" (3.2 mm) long. The plants favor wet areas and disturbed areas.

 

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

7/27/2016 · Michaux State Forest, Caledonia State Park, Fayetteville, PA
≈ 10 × 15" (26 × 39 cm)

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

10/20/2013 · Barrett Park, Leominster, MA
≈ 8 × 5" (19 × 12 cm)

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

10/25/2009 · Nashua River Rail Trail, Nashua, NH
≈ 9 × 6" (23 × 15 cm)

Here is a comparison between giant knotweed and Japanese knotweed:

 
Polygonum sachalinense
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Polygonum cuspidatum
Common Name

Giant Knotweed

Japanese Knotweed
Plant Stems are hollow, and thickly clustered, closely resembling bamboo. Plants are large, up to 13' (4 m) in height. Japanese knotweed stems are jointed and hollow like bamboo. Plants reach up to 12' (3.7 m), but are usually half that.
Flowers Groups of slender cone-shaped panicles, white or greenish in color. In multiple upward pointing spikes containing many tiny white to pale yellow flowers.
Leaves Alternate, ovate (oval, wider at the bottom), cordate (heart-shaped), up to 12" (30 cm) long, with crenate (wavy) edges. Leaves are oval, wider and flat near the base, 2-6" (5-15 cm) long and 1-4" (2.5-10 cm) wide.
Fruit Triangular, with three “wings.” Seed pods are shaped like inverted hearts, about ⅛" (3.2 mm) long.
Range/ Zones

USDA Zones: 5-8

Habitats Rivers, swamps, and other wetland regions. Wet areas and disturbed areas
Type Wild Wild

 

Medical: Historically, extracts from Japanese knotweed have been used to treat menstrual cramps and postpartum depression. Other ingredients aid in treatment of burns; these are also used in skin lotions. There are many other purported but unconfirmed health benefits.

Edibility: Thicker young shoots, gathered early in the spring, can be cooked in boiling water or a steamer and served with butter, like asparagus. And like asparagus, they cook quickly, and should be served as soon as they are easily pricked with a fork. See herbalpedia.

Online References:

Polygonum cuspidatum on Wikipedia

Polygonum cuspidatum at the Washington State Department of Ecology

Polygonum cuspidatum on www.ag.purdue.edu (PDF)

Polygonum cuspidatum on Invasive.org, Center for Invasive Species and Ecosystem Health

Polygonum cuspidatum on the Virginia Tech Weed Identification Guide

Polygonum cuspidatum on CalPhotos

Polygonum cuspidatum on klemow.wilkes.edu (a technical summary of the medical properties)

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

4/24/2016 · Blue Trail, Willard Brook State Park, Ashby, NH

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

10/20/2013 · Barrett Park, Leominster, MA
≈ 8 × 5" (19 × 12 cm)

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

7/27/2016 · Michaux State Forest, Caledonia State Park, Fayetteville, PA
≈ 21 × 14" (52 × 34 cm)

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

4/24/2016 · Blue Trail, Willard Brook State Park, Ashby, NH

Polygonum cuspidatum description by Thomas H. Kent, last updated 10 Oct 2016.

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Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

4/29/2017 · Willard Brook State Park, Ashby, MA
≈ 5 × 8" (13 × 20 cm)

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

10/25/2011 · Nashua River Rail Trail, Dunstable, Dunstable, MA
≈ 15 × 10" (39 × 26 cm)

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

9/24/2010 · Nissitissit River Wildlife Management Area, Pepperell, MA
≈ 11 × 7" (27 × 18 cm)

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

9/3/2009 · Nashua River Rail Trail, Ayer, MA
≈ 9 × 6" (22 × 14 cm)

Polygonum cuspidatum (Japanese Knotweed, Mexican Bamboo)

9/3/2009 · Nashua River Rail Trail, Ayer, MA
≈ 11 × 7" (27 × 18 cm)

Range:

About this map...