Common Name: Japanese knotweed
Family: Polygonaceae
Common Synonyms: Polygonum cuspidatum
USDA Hardiness Zone: 4a - 8b
Growth Habit: Shrub
Origin: Eastern Asia
FISC Category: -
FDACS Listed Noxious Weed: No
Introduction Date: Introduced in US late 1800's, not established in Florida
IFAS Assessment:
Perennial shrub with glabrous stems (mostly not branched) that ascend from a rhizomatous base, to 3 m tall, often forming a dense infestation. Stems reddish, hollow, swollen at nodes, and tend to zigzag slightly from node to node. Alternate leaves are oval-shaped 7-14 cm long and 5-12 cm wide with an entire margin. Axillary panicles with many 5-petaled, tiny, white flowers. Fruits shiny, brown, triangular nuts.
River banks, wetlands, disturbed areas, railways, prefers open sunny habitats
No specimens from FL, closest in central GA. Present in most northern states and Canada. Climate could prevent naturalization in FL but good to monitor. Very fast growth. Predominantly reproduces vegetatively via rhizomes.
**Follow herbicide labels: Only herbicides registered for application in water by EPA and FDACS may be applied to weeds growing in or near water.
Alberternst, B. and H.J. Bohmer. 2011. NOBANIS Invasive Alien Species Fact Sheet Fallopia japonica. Online Database of the European Network on Invasive Alien Species NOBANIS www.nobanis.org. Accessed on December 10, 2013.
CABI. 2013. Japanese Knotweed Alliance. http://www.cabi.org/japaneseknotweedalliance/default.aspx?site=139&page=52. Accessed on December 10, 2013.
Dave's Garden. 2013. PlantFiles: Variegated Japanese knotweed, Speckled Mexican bamboo, Fallopia japonica. http://davesgarden.com/guides/pf/go/57523/. Accessed on December 9, 2013.
Miller, J.H., E.B. Chambliss, and N.J. Loewenstein. 2010. A Field Guide for the Identification of Invasive Plants in Southern Forests. U. S. Department of Agriculture, Southern Research Station. Asheville, NC.