Japanese Knotweed

Names and Synonyms

Common Names

• Japanese knotweed
• Mexican bamboo
• Mexican-bamboo
• Asiatic Knotweed
• Itadori knotweed
• Japanese fleece flower
• donkey rhubarb

Scientific Names

Accepted name

Synonyms

• Reynoutria uzenensis
• Reynoutria japonica f. hastata
• Polygonum cuspidatum var. uzenense
• Polygonum reynoutria f. colorans
• Reynoutria japonica var. spectabilis
• Pleuropterus zuccarinii
• Fallopia japonica
• Polygonum cuspidatum var. spectabile
• Pleuropterus cuspidatus
• Fallopia japonica var. hachidyoensis
• Reynoutria hachidyoensis
• Polygonum cuspidatum f. roseum
• Fallopia japonica var. uzenensis
• Reynoutria hachijoensis
• Reynoutria japonica var. hastata
• Reynoutria henryi
• Polygonum zuccarinii
• Fallopia japonica f. colorans
• Reynoutria hastata
• Tiniaria japonica
• Polygonum hachidyoense
• Reynoutria japonica var. humilis
• Reynoutria yabeana
• Reynoutria japonica var. elata
• Polygonum reynoutria
• Reynoutria japonica f. rosea
• Polygonum pictum
• Reynoutria hachidyoensis var. terminalis
• Polygonum cuspidatum var. hachidyoense
• Reynoutria japonica var. terminalis
• Polygonum cuspidatum var. terminale
• Reynoutria japonica var. uzenensis

Regional and Traditional Names

Sources: Wikidata, Catalogue of Life

Taxonomical Classification

This plant belongs to the kingdom Plantae and is classified under the phylum Streptophyta and class Equisetopsida. Within the subclass Magnoliidae and order Caryophyllales, it is a member of the family Polygonaceae. Finally, it is identified by the genus Reynoutria.

Sources: The World Checklist of Vascular Plants (WCVP)

Distribution

This plant exhibits a significant presence across several regions within Northern Europe. It can be found growing in the coastal and inland areas of Denmark. Its distribution extends further north to include the territories of Finland and the Faroe Islands. Additionally, the species is well-established throughout the landscapes of Great Britain. Finally, its range reaches the emerald landscapes of Ireland.

Sources: The World Checklist of Vascular Plants (WCVP)

Botanical Identification

Ecology

The ecology of Reynoutria japonica is characterized by a broad adaptive capacity across varying altitudes, ranging from sea level (0 m AMSL) up to a maximum elevation of 2000 m AMSL. While the species is frequently found in lowland habitats, it maintains a significant presence across a wide vertical gradient, with a mean elevational range of approximately 1070 m AMSL. This ability to inhabit diverse topographical zones allows it to establish itself in a variety of environmental conditions within its ecological niche.

Elevational range max:

2000 m AMSL

Elevational range mean:

1070 m AMSL

Elevational range min:

0 m AMSL

Habitat :

Lowland

Life history

The life history of Reynoutria japonica is characterized by a perennial lifecycle, allowing the plant to persist across multiple growing seasons through robust underground structures. As a geophyte, it relies heavily on its extensive rhizome system for survival and regeneration, which also classifies it as a cryptophyte, as its perennable buds are protected below the soil surface during unfavorable conditions. Despite its vigorous growth during the active season, its deciduousness profile is categorized as evergreen in certain contexts of biological classification, though it typically undergoes seasonal changes in foliage. This combination of a perennial existence and a geophytic life form enables the species to colonize environments rapidly and endure significant environmental stressors.

Deciduousness :

evergreen

Life form :

geophyte

Life form :

cryptophyte

Lifecycle :

perennial

Morphology

The morphology of Reynoutria japonica is characterized by its growth form as a non-woody herb that functions as a self-supporting plant rather than a liana or vine. It is a terrestrial species, existing as an independent organism without parasitic or epiphytic tendencies. The plant exhibits significant variation in stature, with a height ranging from a minimum of 1 meter to a maximum of 3 meters, resulting in a mean plant height of approximately 1.375 meters.

Aquatic :

terrestrial

Climber :

self-supporting

Epiphyte :

terrestrial

Growth form :

herb

Parasite :

independent

Plant height max:

3 m

Plant height mean:

1.375 m

Plant height min:

1 m

Woodiness :

non-woody

Physiology

The physiology of Reynoutria japonica is characterized by a C3 photosynthetic pathway, indicating its reliance on the standard carbon fixation process typical of many temperate species. As a non-carnivorous plant, it derives all necessary nutrients from the soil and does not possess specialized structures for capturing prey, nor does it function as a nitrogen fixer. The leaf morphology plays a significant role in its resource acquisition, with a mean leaf size of approximately 136.29667 cm² and a mean Specific Leaf Area (SLA) of 189.2 cm²/g, reflecting its investment in leaf surface area relative to biomass. The leaves exhibit considerable variability in dimensions; the mean leaf length is 8.5 cm, ranging from a minimum of 5 cm to a maximum of 18.8 cm, while the mean leaf width is 6.5 cm, with measurements spanning from a minimum of 2 cm to a maximum of 12 cm.

Carnivory :

non-carnivorous

Leaf length max:

18.8 cm

Leaf length mean:

8.5 cm

Leaf length min:

5 cm

Leaf size mean:

136.29667 cm²

Leaf width max:

12 cm

Leaf width mean:

6.5 cm

Leaf width min:

2 cm

Nitrogen fixer :

no

Photosynthetic pathway :

C3

Specific Leaf Area (SLA) mean:

189.2 cm²/g

Reproduction

The reproduction of Reynoutria japonica is characterized by a seasonal flowering period that typically begins in August and concludes in September. During this time, the plant produces inflorescences that range in length from a minimum of 0.03 m to a maximum of 0.08 m. The pollination process is primarily biotic, specifically utilizing an insect pollination syndrome to facilitate fertilization. Notably, self-fertilization is present within the species. Following successful pollination, the plant develops indehiscent fruits categorized as achenes. These fruits are relatively small, with a mean length of 0.375 cm, a minimum length of 0.4 cm, and a maximum length reaching 0.5 cm. The resulting seeds are lightweight, possessing a mean mass of approximately 0.00298175 g, with individual seed masses ranging from a minimum of 0.001017 g to a maximum of 0.00678 g. Dispersal is achieved through a combination of anemochorous (wind-based) and unspecialized mechanisms. While the plant relies on these sexual reproductive methods, asexual reproduction is noted as absent in this specific context.

Dehiscence :

indehiscent

Dispersal syndrome :

anemochorous

Dispersal syndrome :

unspecialized

Flowering time :

Aug

Flowering time :

Sep

Fruit length max:

0.5 cm

Fruit length mean:

0.375 cm

Fruit length min:

0.4 cm

Fruit type :

achene

Inflorescence length max:

0.08 m

Inflorescence length min:

0.03 m

Pollination syndrome :

insect

Pollination syndrome :

biotic

Reproduction asexual :

absent

Seed mass max:

0.00678 g

Seed mass mean:

0.00298175 g

Seed mass min:

0.001017 g

Self fertilization :

present

Sources: Global Inventory of Floras and Traits (GIFT)

Plant Parts

Reynoutria japonica has 2 reported plant parts identified across 5 scientific publications and several other databases that are studied for medicinal purposes. The most consistently reported plant part include rhizome, root.

Rhizome

1. International journal of molecular sciences
2. Pharmaceuticals (Basel, Switzerland)
3. Molecules (Basel, Switzerland)

Root

1. Natural product communications
2. Journal of ethnopharmacology

Chemicals

Reynoutria japonica has 74 reported phytochemicals identified across 5 scientific publications and several other databases. The most consistently reported chemicals include Stilbenes, emodin, resveratrol, Anthraquinones, Piceid.

Stilbenes

1. Dr. Duke
2. International journal of molecular sciences
3. Planta medica
4. Scientific reports
5. Plants (Basel, Switzerland)

emodin

1. Dr. Duke
2. Combinatorial chemistry & high throughput screening
3. Planta medica
4. Pharmaceuticals (Basel, Switzerland)
5. PloS one

resveratrol

1. Dr. Duke
2. Planta medica
3. Pharmaceuticals (Basel, Switzerland)
4. Journal of ethnopharmacology
5. Journal of plant physiology

Anthraquinones

1. Dr. Duke
2. Scientific reports
3. Frontiers in pharmacology
4. Journal of plant physiology

Piceid

1. Dr. Duke
2. Planta medica
3. Pharmaceuticals (Basel, Switzerland)

Polydatin

1. Dr. Duke
2. Yao xue xue bao = Acta pharmaceutica Sinica
3. Journal of ethnopharmacology

(+)-catechin

1. Dr. Duke
2. Natural product communications

Physcion

1. Planta medica
2. PloS one

Procyanidins

1. Scientific reports
2. Molecules (Basel, Switzerland)

polyphenols

1. Pharmaceuticals (Basel, Switzerland)
2. Nutrients

Activities

Reynoutria japonica has 343 reported activities identified across 5 scientific publications and several other databases. The most consistently reported activities include Anticancer, Antioxidant, Antitumor, Cytotoxic, Hepatoprotective.

Anticancer

1. Dr. Duke
2. Molecules (Basel, Switzerland)

Antioxidant

1. Dr. Duke
2. Molecules (Basel, Switzerland)

Antitumor

1. Dr. Duke
2. Molecules (Basel, Switzerland)

Cytotoxic

1. Dr. Duke
2. Molecules (Basel, Switzerland)

Hepatoprotective

1. Dr. Duke
2. Molecules (Basel, Switzerland)

5-HETE-Inhibitor

1. Dr. Duke

5-HT-Inhibitor

1. Dr. Duke

5-Lipoxygenase-Inhibitor

1. Dr. Duke

ACE-Inhibitor

1. Dr. Duke

AGEs-Inhibitor

1. Dr. Duke

Medicinal Uses

Reynoutria japonica has 18 reported medicinal uses identified across 5 scientific publications and several other databases. The most consistently reported uses include COVID-19, Mycobacterium smegmatis, Staphylococcus aureus, burns, cancer.

Most Reported Uses

Preparations