Fauna
Plant

Low Smartweed

Persicaria longiseta

Also known as Oriental Lady's Thumb, Bristly Lady's Thumb, Asiatic Smartweed, Long-bristled Smartweed

Low smartweed forms dense sprawling mats along woodland margins, damp garden beds, and urban waste areas, producing vibrant cylindrical spikes of deep pink to purple flowers from early summer into late autumn. It is easily distinguished from closely related knotweeds by the unusually long, stiff bristles that project from the fringes of the papery sheaths encircling each leaf node. Rapid seed production and high shade tolerance enable it to quickly carpet disturbed soils, often forming continuous understory layers.

HerbaceousFloweringIntroduced
Low Smartweed reference
(c) Andrew Garn, some rights reserved (CC BY), uploaded by Andrew Garn · cc-by
—observations
—countries
—peak records
Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preyPhotoautotrophic
Predators
  • Japanese Beetles
  • Songbirds
  • White-tailed Deer
ThreatsHerbicides, mechanical weeding, lawn mowing
HabitatsDisturbed soil, roadsides, damp woods, lawns, stream edges
Life spanAnnual
Classification
  1. OrderCaryophyllales
  2. FamilyPolygonaceae
  3. GenusPersicaria
  4. SpeciesPersicaria longiseta
Range & activity
Range data is not available yet.
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Safe to observe at a normal distance.
Responsible observation
  • Identifying Sheaths: Use a hand lens to examine the ocrea at the leaf nodes, where long, stiff bristles confirm the ID.
  • Disturbed Habitats: Look for sprawling colonies in shaded park edges, damp gravel paths, and vegetable gardens.
  • Seasonal Timing: Search for vivid rose-pink flower spikes between midsummer and the first hard frost.
Related species
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