Persicaria (Polygonum) 

(pol-e-go-num')

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

Species:

The following are the most available in the U.S.
 
Species zone height flowers native other
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


Cultivars:

The following are the more popular and available in the U.S.
 
Cultivar species flowers other
'Border Jewel' affine pink red foliage in fall
'Crimson Beauty' japonicum crimson  
compactum japonicum reddish brown 2' tall, compact
'Darjeeling Red' affine deep pink  
'Dimity' affine 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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