Persicaria chinensis (Chinese knotweed)

Plate 1 figs. a–h · 8 separate observations

Persicaria chinensis, photographed by 雲一百香果 — fig. a 雲一百香果, CC BY 4.0 / 2022-06-03 / obs. 202848252

Persicaria chinensis, photographed by Licheng Shih — fig. b Licheng Shih, CC BY 4.0 / obs. 185848323

Persicaria chinensis, photographed by Dinesh Valke — fig. c Dinesh Valke, CC BY-SA 4.0 / obs. 183521321

Persicaria chinensis, photographed by 葉子 — fig. d 葉子, CC0 1.0 / obs. 189386437

Persicaria chinensis, photographed by 謝麗霦 — fig. e 謝麗霦, CC BY 4.0 / obs. 179713994

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

Native range 27 botanical countries

Native distribution of Persicaria chinensis, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows. Regions too small to draw at this scale are marked with a dot.

Region	TDWG code	Continent
Assam	ASS	ASIA-TROPICAL
Bangladesh	BAN
Cambodia	CBD
East Himalaya	EHM
India	IND
Jawa	JAW
Laos	LAO
Lesser Sunda Is.	LSI
Malaya	MLY
Myanmar	MYA
Nepal	NEP
Nicobar Is.	NCB
Philippines	PHI
Sri Lanka	SRL
Sumatera	SUM
Thailand	THA
Vietnam	VIE
West Himalaya	WHM
China North-Central	CHN	ASIA-TEMPERATE
China South-Central	CHC
China Southeast	CHS
Hainan	CHH
Japan	JAP
Korea	KOR
Nansei-shoto	NNS
Taiwan	TAI
Tibet	CHT

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Flowering 350 in flower of 443 examined

84%

70%

68%

67%

85%

73%

43%

57%

60%

90%

88%

86%

Proportion of examined Persicaria chinensis in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	56	67	84%	73% to 91%
Feb	21	30	70%	52% to 83%
Mar	21	31	68%	50% to 81%
Apr	34	51	67%	53% to 78%
May	17	20	85%	64% to 95%
Jun	8	11	73%	43% to 90%
Jul	3	7	43%	16% to 75%
Aug	8	14	57%	33% to 79%
Sep	9	15	60%	36% to 80%
Oct	38	42	90%	78% to 96%
Nov	72	82	88%	79% to 93%
Dec	63	73	86%	77% to 92%

Peak flowering in Oct. Each bar is the share of Persicaria chinensis observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 350 of 443 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Where it actually grows measured, from 2,028 observations

Condition	5th percentile	Median	95th percentile
Coldest month, mean daily low	1.6 °C	11.0 °C	14.7 °C
Warmest month, mean daily high	18.9 °C	28.2 °C	31.2 °C
Annual rainfall	1,734 mm	3,297 mm	4,662 mm
Rainfall in the driest quarter	88 mm	220 mm	813 mm

It is found where winters are cool but frost is light or absent. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 2,028 research-grade observations of Persicaria chinensis that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.

This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one. Climate from CHELSA V2.1 (Karger et al. 2017); occurrences from 10.15468/dl.cgje2x.

Also published as 1 synonym

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

Polygonum chinense L.

Sourcesevery claim on this page

World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
USDA PLANTS Database. common name, checklist symbol POCH6. public domain. Retrieved 2026-07-13.
Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.