Bohemian knotweed
Reynoutria × bohemica · Aquatic plants
Whole plant · Photo: CC0
Also called Polygonum x bohemicum, Hybrid knotweed, Fallopia x bohemica
State noxious weed listing
- Idaho: Control
- Oregon: B list
How to identify Bohemian knotweed
- Hollow, bamboolike canes 6 to 15 feet
- Leaves 6 to 12 inches with a straight to slightly heart shaped base
- Short, stiff hairs on the veins of the leaf underside (use a hand lens)
- Creamy white flower sprays in late summer
Similar plants
Japanese knotweed has smaller leaves with a squared off base and no hairs underneath; giant knotweed has larger leaves with a deep heart shaped base and long wavy hairs underneath.
Growth profile
| Growing season | Shoots come up in April and May, flower August and September and die back at frost. |
|---|---|
| Starts growing | Spring |
| Light | Full sun to part shade |
| Depth | Moist banks above the waterline |
| How it spreads | Rhizomes, stem fragments and seeds |
| Habitat | Streambanks, gravel bars, pond edges, ditches and roadsides. |
Why it matters in a lake
A hybrid of Japanese and giant knotweed that is often mistaken for Japanese knotweed; in western Washington it is the most common invasive knotweed. Control is the same as for Japanese knotweed and takes several years.
Where it is found
- Idaho: Occasional
- Oregon: Occasional
- Wyoming: Not recorded
Classification
| Kingdom | Plantae |
|---|---|
| Phylum | Tracheophyta |
| Class | Magnoliopsida |
| Order | Caryophyllales |
| Family | Polygonaceae |
| Scientific name | Reynoutria × bohemica |
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