Spermatophytes (seed plants): Angiosperms (flowering plants): Eudicots: Core Eudicots: Caryophyllales
WEAKLEY'S FLORA (11/30/12):
Reynoutria japonica
FAMILY
Polygonaceae
Dig deeper at SERNEC, a consortium of southeastern herbaria.
Check out EDDMapS.org to see where this has been reported.
Read Newsweek's article on Japanese Knotweed: The Invasive Plant That Eats the Value of Your Home
Read more about Japanese Knotweed at Vascular Plants of North Carolina.
SYNONYMOUS WITH
PLANTS NATIONAL DATABASE:
Polygonum cuspidatum
FAMILY
Polygonaceae
SYNONYMOUS WITH
Generic Limits in Polygonum (Ronse Decraene & Akeroyd, 1988)
Fallopia japonica
SYNONYMOUS WITH
VASCULAR FLORA OF THE CAROLINAS (Radford, Ahles, & Bell, 1968) 063-04-023:
Polygonum cuspidatum
FAMILY
Polygonaceae
SYNONYMOUS WITH
Manual of the Southeastern Flora (Small, 1933)
Pleuropterus zuccarinii
COMMON NAME:
Japanese Knotweed
To see larger pictures, click or hover over the thumbnails.
)
USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913 pnd_plzu_001_lvd
)
JK Marlow jkm160322_058
March Greenville County SC
Riparian zone along urban waterway
Stems erect, stout, striate, papillate, often with red or purple spots, per Flora of China.
)
JK Marlow jkm160322_059
March Greenville County SC
Riparian zone along urban waterway
Ocrea oblique, per Flora of China.
)
JK Marlow jkm160331_184
March Greenville County SC
Riparian zone along urban waterway
)
JK Marlow s050406_a
April Greenville County SC
Roadside
Mid-branch leaves truncate (to very broadly V-shaped), per Weakley's Flora (2012).
)
JK Marlow jkm130628_308
June Cherokee County NC
Murphy River Walk
)
JK Marlow jkm0407a_37
July Greenville County SC
Mortgage lenders in the UK may refuse to loan on property with Japanese Knotweed
)
JK Marlow jkm0407b_08
July Greenville County SC
Roadside
)
JK Marlow jkm0407b_13
July Greenville County SC
Roadside
Flowers in axillary, paniculate racemes. Calyx 1.5-2mm long in flower, per Vascular Flora of the Carolinas.
)
JK Marlow s080705_a
July Swain County NC
Veins of leaf underside minutely scabrous with scattered bumps, per Weakley's Flora (2012).
)
JK Marlow jkm160818_631
August Polk County NC
Pearson's Falls
)
JK Marlow jkm160818_632
August Polk County NC
Pearson's Falls
WEAKLEY'S FLORA (11/30/12):
Reynoutria japonica
FAMILY
Polygonaceae
SYNONYMOUS WITH
PLANTS NATIONAL DATABASE:
Polygonum cuspidatum
FAMILY
Polygonaceae
SYNONYMOUS WITH
Generic Limits in Polygonum (Ronse Decraene & Akeroyd, 1988)
Fallopia japonica
SYNONYMOUS WITH
VASCULAR FLORA OF THE CAROLINAS (Radford, Ahles, & Bell, 1968) 063-04-023:
Polygonum cuspidatum
FAMILY
Polygonaceae
SYNONYMOUS WITH
Manual of the Southeastern Flora (Small, 1933)
Pleuropterus zuccarinii
1122
Forb
Perennial
Monoecious or dioecious
Non-native: East Asia
Documented growing wild in GA NC SC
Uncommon in GA-NC-SC
Look for it on roadsides, disturbed areas, riverbanks and sandbars, often forming dense thickets, per Weakley's Flora
Click here to see a more detailed map from University of North Carolina at Chapel Hill Herbarium,
or click here to see a map from SERNEC, a consortium of southeastern herbaria.
This plant is causing problems in natural areas outside its native range, according to authorities such as:
- Alabama Invasive Plant Council, 2012
- Brooklyn Botanic Garden
- Georgia Exotic Pest Plant Council, 2006
- Kentucky Exotic Pest Plant Council, 2013
- NC Department of Transportation
- SC Exotic Pest Plant Council, 2014
- Tennessee Exotic Pest Plant Council, 2009
- US Fish & Wildlife Service
- US Forest Service Southern Research Station
- Virginia Department of Conservation and Recreation, 2014
LEAVES:
Simple
Alternate
Margins entire
FLOWER:
Spring/Summer/Fall
Calyx white
(rarely tinged with pink)
Functionally unisexual
5-parted calyx
Petals absent
8 stamens
Superior ovary
Flowers in axillary paniculate racemes
FRUIT:
Summer/Fall
Brown, lustrous
Nutlet
TO LEARN MORE about this plant, look it up in a good book!
- Guide to the Wildflowers of SC p390
- Invasive Plants, Guide to Identification, Impacts and Control p258
- A Field Guide for the Identification of Invasive Plants in Southern Forests p042
- Invasive Exotic Plants of North Carolina p041
- Newcomb's Wildflower Guide p190
- Wildflowers of the Eastern United States p004
- Wildflowers of the Southern Mountains p032