Japanese, Giant and Bohemian Knotweed

Also known as Fleece flower, Mexican bamboo or Elephant ear bambooinject (1)
Polygonum Cuspidatum 
Quick ID:
  • Grows to heights in excess of 10 feet
  • Stems are smooth, bamboo-like and stout
  • Stems are hollow, but may be water-filled depending upon soil moisture and time of year

Habitat:

  • Found in parks, gravel bars, along riverbeds, stream banks, rights-of way, and roadsides. It is also found in riparian areas and will move up river columns.

How It Got Here:

  • Originated from Asia and spread west for the last few hundred years (primarily by fragmentation)
  • 10mm of plant can re-grow to maturity.
  • New Bohemian Variety can propagate by fragmentation and flowering to seed.

Reasons for Concern:

  • Can invade and thrive in a variety of habitats with no natural predators or control mechanisms.
  • Knotweed has evolved in the Bohemian variety found in North America now on both coasts to propagate by seed and fragmentation.  Neither of the other dominant strains had both capabilities.  This likely explains the rapid progress observed in the Americas as opposed to the rather slow progression of the UK and Asiatic strains.  
  • Knotweed rapidly reproduces through seeds, rhizomes, and will move quickly down a riverbed and create one solid monoculture infestation.
  • Canes can sprout through 6 inches of concrete or asphalt. (roads & foundations)

 

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