My home is near a decommissioned “yard and garden waste dump”. This has one small advantage for me; whenever I want to photograph a local weed or invasive plant, I’m pretty much guaranteed to find it nearby–and in quantity. In the wider-angle shot, you can see three of southwestern British Columbia’s worst invasives on the slope of a berm: Rubus armeniacus (Himalayan blackberry), Cytisus scoparius (Scot’s broom) and today’s plant, Fallopia japonica (Japanese knotweed).
Biologist Dr. Jennifer Forman Orth has created a web site devoted to Japanese knotweed. The site includes details on this plant’s many scientific and common names, appearance throughout the year and control measures. Another site with excellent information is the UK-based Japanese Knotweed Alliance.
Nomenclaturally, it is noteworthy that the scientific name for this plant seems not to be agreed upon by taxonomists; North Americans generally use Polygonum cuspidatum Sieb. & Zucc. (but the Flora of North America does not), while Europeans tend to use Fallopia japonica (Houtt.) Dcne. The distinction centres on whether the genus Fallopia is recognized scientifically and genetically as being distinct from Polygonum.
Botany / conservation resource link: Invasive Species Weblog. Another web site by Dr. Orth, the Invasive Species Weblog tracks the spread of invasive species around the world. From my perspective, there are few other science webloggers as inspiring as Jenn (I can call her that since that’s how she posted her name in a comment on the BPOTD entry for Lonicera ‘Mandarin’). Since early 2002, she has written almost daily about the impact of invasive species on natural communities. To top it off, her writing style makes the subject matter approachable by people of any biological background, from none to expert.