T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Persicaria capitata (Pink Knotweed)

Kingdom: Plantae
(Unranked): Angiosperms
(Unranked): Eudicots
(Unranked): Core eudicots
Order: Caryophyllales
Family: Polygonaceae
Genus: Persicaria
Species:  P. capitata
Binomial name: Persicaria capitata
Synonyms: Polygonum capitatum
Common names: Pink-head knotweed, Pink Knotweed, Japanese Knotweed or Pink bubble persicaria.

Persicaria capitata is a native of Asia. It is a tailing, perennial, evergreen prostrate herb with a slender, woody rootstock and long slender, creeping, rooting stems.  It has alternate ovate leaves are 1–6 cm long, 0.7–3 cm wide with a reddish midrib with fine coloured hairs, giving a distinctive red ‘V’ pattern, The leaves become red when the plant is under stress.
This plant has a strong urine scented odour. It develops ball-like inflorescences (7-20 mm across) of numerous pink flowers (2.5-3 mm long). Flowering occurs during Oct-Mar. it produces a small (1.5 mm long) and brown nut.
Persicaria capitata is found growing on roadsides, dry banks & slopes, open areas preferring full sun. Its impact on the environment is that it forms a dense carpet replacing most native vegetation. It spreads locally from trailing stems that root easily and also garden dumping.
Persicaria capitata has been widely used in China in the treatment of various urologic disorders including urinary calculus and urinary tract.

Plant not under stress hence green leaves.

Persicaria capitata leaves (not the flowers)

The underside of the leaves

Red foliage when the plant is under stress.


Persicaria capitata growing in full sunlight and is a stress situation hence the red leaves.

Persicaria capitata growing in part shaded area.

Young leaves of Persicaria capitata

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/