Japanese Knotweed

(Polygonum cuspidatum)

Other Names:
(syn. Fallopia japonica, Reynoutria japonica)

Range:


Family:
Polygonaceae – Buckwheat family

Growth Type:
An invasive species, Japanese Knotweed is a tall shrub-like weed that grows in large colonies.

Height:
Can grow to 9 - 12 feet tall, although usually found much smaller

Leaves:
The leaves are spade shaped, and can be rather large. They are relatively flat at the base, and pointed at the tip, just like the end of a spade.

Stem/Trunk:
The stems are hollow with enlarged nodes, just like bamboo. During the winter, stands are easily identified as they look like stands of dried bamboo.

Root:
Rhizome

Flower Season:
Late Summer and Early Autumn

Flower Appearance:
The flowers are small, cream or white, produced in erect racemes 6–15 cm long

Seed/Fruit:
N/A

Miscellaneous characteristics:
An invasive species native to eastern Asia in Japan, China and Korea, which has become widespread throughout the US.

Habitat:
Disturbed soils, yards, old homesteads, roadsides

Parts Used:
Young Shoots as food. Roots for medicinal purposes.

Culinary Uses:
The young shoots can be eaten raw, or cooked. they have a sour almost rhubarb-like taste. I have heard they can be used in pies, but I have not tried this myself. Some caution should be taken when consuming this plant, as it contains oxalic acid. There is a possibility that in very large quantities oxalic acid may aggravate conditions such as rheumatism, arthritis, gout, kidney stones or hyperacidity.

Energetics
Taste: Sour
Thermal: Warming
Humidity: Drying

Traditional Medicinal Uses:
Japanese knotweed is a concentrated source of emodin, which has been used to regulate bowel function and motility. The roots of Japanese knotweed are used in traditional Chinese and Japanese herbal medicines as a natural laxative. The effective dosage has been 20 to 50 mg per day. The root has also been used in Korea to maintain oral health. It has been shown to reduce the viability of Streptococcus mutans and Streptococcus sobrinus. The roots of Polygonum cuspidatum contain Resveratrol. There have been recent studies which have shown this phenol to be effective at improving cardiac health, immune function, and supporting cognition. Here is a link to a published paper concerning the health benefits of P. cuspidatum.

Medicinal Actions:
Adaptogen, Antibacterial, Antifungal, Antimicrobic, Antineoplastic, Antioxidant, Antiviral, Aperient, Astringent, Cathartic, Laxative