Common name: Knotweed, Smartweed, European Bistort, Fleeceflower, Silver Lace Vine
Family: Polygonaceae, Knotweed
Height x width: 9-24" x 12-24"
Growth rate: fast; spreading; some species invasive (especially Japanese knotweed, P. japonica)
Foliage: basal leaves, depending on species 3-9" long and 1-5" wide, dark green often with prominent white midvein, stem leaves on some species
Flowers: tightly clustered spike 2-4" long on a leafless stalk (peduncle) above foliage, summer, pink to red
Hardiness: zones 3-5 to 7
Soil: constantly moist, tolerates drier if shade or wetter
Light: sun tolerates and spreads less in part shade
Pests and Problems: few, occasionally leaf spots, mites, scorching of leaves if too dry
Landscape habit, uses: moist borders where it can be contained or managed, wet areas along ponds (not along streams as roots can be translocated and invade other areas), stabilize moist slopes, large rock garden; aggressive habit
Other interest: related to one of most pernicious weeds of north Japanese Bamboo (P. japonicum) although ornamental species much less agressive and easier to manage, still often regarded as weedy; popular in England and Europe; genus name from the Greek polys meaning many and gonu meaning swollen, refering to the swollen stem nodes; taxonomists have split the genus into two other genera Persicaria and Fallopia, although it is still often seen in usage as Polygonum. One of the most popular cultivars 'Painter's Pallette' was first moved to the genus Tovara, but then back to Persicaria virginiana.
Other culture: plant only where it can spread, or allow for this!
Propagation: stem cuttings, spring division, seeds
The following are the most available in the U.S.
|affine||3-7||8-12"||pink, red||Himalaya||leaves reddish in fall|
|amplexicaulis||5-7||2-3'||red, purple, white||Himalaya||woody rootstock|
|aubertii||4-7||10-15'||white, fragrant||Asia||woody twining vine|
|bistorta||4-7||18-24"||rose, white||Eurasia||wavy leaf margins|
|capitatum||8-9||4"||pink spheres||Himalaya||creeping, non-hardy|
|japonica||4-9||2-6'||creamy||E. Asia||species is noxious weed|
|vaciiniifolia||7-9||6-12"||pink||Himalaya||trailing, woody stems|
|virginiana||5-7||2-3'||pink||Asia||late summer flowers|
|weyrichii||5-7||3-5'||greenish white||E. Russia||leaves whitish below|
The following are the more popular and available in the U.S.
|'Border Jewel'||affine||pink||red foliage in fall|
|compactum||japonicum||reddish brown||2' tall, compact|
|'Darjeeling Red'||affine||deep pink|
|'Donald Lowndes'||affine||salmon pink||double flowers|
|'Firetail'||amplexicaulis||crimson, 6" long||heart-shaped clasping leaves|
|'Himalayan Border Jewel'||affine||light pink, small|
|'Inverleith'||amplexicaulis||dark crimson||short spikes|
|'Magic Carpet'||capitatum||pink||compact, not hardy|
|'Painter's Pallette'||virginiana||red||leaves white, pink, v-shaped red center|
|'Superbum'||affine||pink fading red||vigorous|
|'Superbum'||bistorta||pink||larger flowers than species|
©Authored by Dr. Leonard Perry, Professor, University of Vermont as part of PSS123 course.
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