Bohemian Knotweed
Fallopia x bohemica
Physical Description
Bohemian knotweed is a vigorous, fertile hybrid resulting from a cross between Japanese and giant knotweed. In the Pacific Northwest it is believe that only a male sterile clone of Japanese knotweed exists, not capable of producing viable seed however, the presence of giant knotweed in close proximity may provide the potential viable pollen required for hybrid offspring. There is evidence that a large percentage of the Japanese knotweed in the Pacific Northwest is actually bohemian. The amount actual seed production from this hybrid is not clear. What is clear, based on our years of survey and monitoring of Lincoln County knotweed, is that there exist a high level of morphological variability in Lincoln County Japanese knotweed infestations and that some level of hybridization is going on in our river basins. Viable seed production of Lincoln County knotweed has not been assessed.
Bohemian knotweed is a vigorous, fertile hybrid resulting from a cross between Japanese and giant knotweed. In the Pacific Northwest it is believe that only a male sterile clone of Japanese knotweed exists, not capable of producing viable seed however, the presence of giant knotweed in close proximity may provide the potential viable pollen required for hybrid offspring. There is evidence that a large percentage of the Japanese knotweed in the Pacific Northwest is actually bohemian. The amount actual seed production from this hybrid is not clear. What is clear, based on our years of survey and monitoring of Lincoln County knotweed, is that there exist a high level of morphological variability in Lincoln County Japanese knotweed infestations and that some level of hybridization is going on in our river basins. Viable seed production of Lincoln County knotweed has not been assessed.
- Broadly ovate to narrowly ovate leaf with a flat to heart shaped base (7-14 inches long)
- Green with or without red to brown spotting, thin to wide, segmented stems 6-11 ft tall
- Short, stout leaf hairs, up to 1/2 mm long
- Middle leaf vein square to slightly rounded in cross section
- Papery sheaths between stem sections
- Hollow stems
- Cream colored, sweet smelling, linear flower bunches at each leaf, often with a more stout, upright appearance than Japanese or giant knotweed.
- Male fertile and male sterile plants
Spectrum of leaf shapes of Japanese, giant and hybrid bohemica knotweed species
