Drooping knotweed

Family • Polygonacea - Polygonum pubescens Blume - La liao

Scientific names

Polygonum pubescens Blume
Polygonum flaccidum Hook. f.
Polygonum roettleri Roth.
Persicaria pubescens (Blume) H. Hara

Common names

Drooping knotweed (Engl.)

Other vernacular names

CHINESE: Fu mao liao, Ban jiao cao, Chui liao, La liao cao, Ruan jing shui liao.
JAPANESE: Bontoku tade.

Drooping knotweed

Additional Sources and Suggested Readings

(1) Traditional knowledge of Adi tribe of Arunachal Pradesh on plants / R C Srivastava and Adi community / Indian Journ of Traditional Knowledge, Vol 8(2), April 2009, pp 146-153

(2) Accumulation characteristics of Cd in Polygonum pubescens Bl. / Deng Hua / Agricultural Science and Technology (Jun. 2010)

Drooping knotweed2
Polygonum pubescens is a perennial herb, much taller than Polygonum hydropiper, up to 75 centimeters tall. Leaves are stalkless, 5 to 15 centimeters long, smooth or hairy. Pinkish-red flowers are borne in drooping racemes, 15 centimeters long, and slender. Nut is small, black, and minutely granular.

– In swampy places at low altitude in Cagayan Province in Luzon.
– Also occurs in India, China, Taiwan and Malaya.

Emmenagogue, abortifacient.

– Leaves used as potherb or seasoning.

Drooping knotweed3

– In China the bruised plant is applied locally to blistered and swollen feet.
– Used for snake bites.
– Also used as emmenagogue and abortifacient.

– In India’s Arunachal Pradesh, whole plant paste is thrown into the stream to stupefy the fish, make them float up for an easy catch.

Study Findings
• Phytoremediation / Cadmium: Study evaluated the accumulation characteristics of Cd in Polygonum pubescens. Under all test concentrations, Cd content in the roots and shoots exceeded 100 mg/kg and the enrichment coefficient over 1. Results showed P. pubescens has high tolerance and accumulation capacity of Cd, with a potential on phytoremediation of Cd-contaminated soil.