Spermatophytes (seed plants): Angiosperms (flowering plants): Eudicots: Core Eudicots: Caryophyllales
WEAKLEY'S FLORA OF THE SOUTHEASTERN US (4/24/22):
Reynoutria japonica
FAMILY
Polygonaceae
Go to FSUS key
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 Floristic Synthesis of North America. BONAP (Kartesz, 2021)
Reynoutria japonica
SYNONYMOUS WITH Flora of North America
Fallopia japonica var. japonica
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, 1938)
Pleuropterus zuccarinii
COMMON NAME:
Japanese Knotweed, Japanese Bamboo, Japanese Buckwheat
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 (Radford, Ahles, & Bell, 1968).
)
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 OF THE SOUTHEASTERN US (4/24/22):
Reynoutria japonica
FAMILY
Polygonaceae
SYNONYMOUS WITH
PLANTS NATIONAL DATABASE:
Polygonum cuspidatum
FAMILY
Polygonaceae
SYNONYMOUS WITH
Floristic Synthesis of North America. BONAP (Kartesz, 2021)
Reynoutria japonica
SYNONYMOUS WITH
Flora of North America
Fallopia japonica var. japonica
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, 1938)
Pleuropterus zuccarinii
1122
Forb
Perennial
Monoecious or dioecious
Habitat: Roadsides, disturbed areas, river banks and sandbars, often forming dense thickets, per Weakley's Flora
Non-native: east Asia
Uncommon (rare in GA Coastal Plain)
Click here to see a map, notes, and images from Weakley's Flora of the Southeastern US.
Click here to see a map showing all occurrences known to SERNEC, a consortium of southeastern herbaria. (Zoom in to see more detail.)
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 (Porcher & Rayner, 2001) p390
- Invasive Plants, Guide to Identification, Impacts and Control (Kaufman & Kaufman, 2007) p258
- A Field Guide for the Identification of Invasive Plants in Southern Forests (Miller, Chambliss, & Lowenstein, 2010) p042
- Invasive Exotic Plants of North Carolina (Smith, 2008) p041
- Newcomb's Wildflower Guide (Newcomb, 1977) p190
- Wildflowers of the Eastern United States (Duncan & Duncan, 1999) p004
- Wildflowers of the Southern Mountains (Smith, 1998) p032