Hybrid Japanese Knotweed (Fallopia x bohemica)

 
 
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Description
Hybrid Japanese Knotweed grows, on average, to a height of 2.5 - 3 m, although plants up to 4 m have been recorded. Leaves are up to 25 cm long and 18 cm wide, with variable leaf base shape. Leaves are usually longer than they are wide, pointed at the tip, slightly crinkled in appearance, with short white hairs (trichomes) growing on the veins on the underside – particularly in the early part of the growing season. Veins are usually reddish purple in immature leaves. Rhizomes have a less prominent color internally and can be bleached out completely to white. An absence of crowns has been noted during excavations. Creamy-white flowers appear in dense clusters in late summer/early autumn.

Key Identifiers
  • Bamboo like stems
  • Often forms extensive rhizomatous root system colonies
  • Hairs on the leaf undersides, especially along the midvein, are short and broad-based (triangular-shaped). These hairs are easiest to see with a hand lens during the spring and summer, often falling off later in the season.
  • Flower clusters are generally about the same length as the below leaf. Leaf and flower characters are most reliable when looking near the middle of a branch.
Location in Canada
BC, NS and Quebec all report the presence of Hybrid Japanese Knotweed. Alberta is suspected to have a few ornamental locations of unconfirmed knotweed.

Robert Vidéki, Doronicum Kft., Bugwood.org

Robert Vidéki, Doronicum Kft., Bugwood.org

Resources Similar species
Giant Knotweed (F. sachalinensis) can be distinguished by the leaves, which are usually 20-40 cm, deeply indented at the base, leaf tip pointed, leaf texture thin and flexible.

Japanese Knotweed (F. japonica) can be distinguished by the leaves, which are usually 3-10 cm, straight at the base, leaf tip abruptly pointed, leaf texture thick and leathery.

Elderberries (Sambucus spp.) have lance-shaped, pointed, and sharply toothed leaflets.
 
 
 
 

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For more information about the content of this document, contact Nicole Kimmel.
This document is maintained by Shelley Barkley.
This information published to the web on April 11, 2012.
Last Reviewed/Revised on March 21, 2014.