Spermatophytes (seed plants): Angiosperms (flowering plants): Eudicots: Core Eudicots: Caryophyllales
WEAKLEY'S FLORA OF THE SOUTHEASTERN US (4/14/23):
Reynoutria japonica var. 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.
INCLUDED WITHIN
PLANTS NATIONAL DATABASE:
Polygonum cuspidatum
FAMILY
Polygonaceae
INCLUDED WITHIN Floristic Synthesis of North America. BONAP (Kartesz, 2021)
Reynoutria japonica
SYNONYMOUS WITH Flora of North America north of Mexico, vol. 5 (2005)
Fallopia japonica var. japonica
INCLUDED WITHIN Floristic Synthesis of North America (Kartesz, 1999)
Polygonum cuspidatum
INCLUDED WITHIN Generic Limits in Polygonum (Ronse Decraene & Akeroyd, 1988)
Fallopia japonica
INCLUDED WITHIN VASCULAR FLORA OF THE CAROLINAS (Radford, Ahles, & Bell, 1968) 063-04-023:
Polygonum cuspidatum FAMILY Polygonaceae
INCLUDED WITHIN 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 (4/14/23):
Reynoutria japonica var. japonica
FAMILY
Polygonaceae
INCLUDED WITHIN
PLANTS NATIONAL DATABASE:
Polygonum cuspidatum
FAMILY
Polygonaceae
INCLUDED WITHIN
Floristic Synthesis of North America. BONAP (Kartesz, 2021)
Reynoutria japonica
SYNONYMOUS WITH
Flora of North America north of Mexico, vol. 5
Fallopia japonica var. japonica
INCLUDED WITHIN
Floristic Synthesis of North America (Kartesz, 1999)
Polygonum cuspidatum
INCLUDED WITHIN
Generic Limits in Polygonum (Ronse Decraene & Akeroyd, 1988)
Fallopia japonica
INCLUDED WITHIN
VASCULAR FLORA OF THE CAROLINAS (Radford, Ahles, & Bell, 1968) 063-04-023:
Polygonum cuspidatum
FAMILY
Polygonaceae
INCLUDED WITHIN
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
Common in Mountains & in NC, rare in GA Coastal Plain, uncommon elsewhere in GA-NC-SC
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)
5-parted calyx
Petals absent
8 stamens
Superior ovary
Functionally unisexual
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, 1st ed. (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
If a search such as "Carex leptalea var. leptalea" doesn't deliver the results you want, try "Carex leptalea".
Or, to minimize chances of a misspelling, try just "Carex le".
Less is more: If "pencil flower" doesn't deliver the results you want, try "pencil".