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Common Knotweed Polygonum aviculare 

 
 
Attracts BeesBees are attracted to this plant
Attracts HoverfliesHoverflies are attracted to this plant
Annual Life CycleAnnual life cycle
Cup-Shaped FlowersCup-shaped flowers
White FlowersWhite flowers
5 Petals5 petals
Jun-Nov Flowering
period
Oval LeavesOval leaves
Crinkly-Edged LeavesCrinkly-edged leaves
Round StemRound stem
Tap RootTap root
30cmMaximum height
 
 
  Main image of Common Knotweed

© 2020-2025 Adrian Briggs

 

Common Knotweed is a native annual plant of the UK, typically found growing in cropland, gardens and waste ground, to a mature height of up to 30cm.

The name 'Knotweed' or 'Knotgrass' is used as a descriptive name for plants which have 'knots' formed of swollen growth nodes, covered by papery sheaths, where branching occurs and where leaves and flowers emerge directly from the stem. The genus name 'Polygonum' is thought to derive from 'many joints' (referring to the swollen nodes) or 'many seeds' (as each plant can produce about 6,000 seeds). The species name 'aviculare' meaning 'small bird' may refer to the plant's attraction for seed-eating birds or may be descriptive of the appearance of the emerging pointed fruits as they ripen in a 'nest' of small tepals.

Botanic classification and naming: Common Knotweed is a member of the Knotweed (Polygonaceae) family. The genus name 'Polygonum' identifies the plant as a Knotweed and its species name 'aviculare' means 'small bird'.

Concerns: Knotweed can be a persistent weed of agricultural land as its seeds remain viable for many years, germinating when the soil is disturbed and they reach light. It also has tough roots, making it difficult to remove.

Benefits: Provides a food source for seed-eating birds.

Benefits to wildlife are also indicated with orange icons in the plant profile bar at the top.

 

 
Flower of Common Knotweed

© 2021 Adrian Briggs

 

Flowers:
Common Knotweed usually flowers between June and November.

Flower colour:

Flower Colour White

White

Flower shape:

Flower Shape  Cup

Cup

Petals:

Petal Number =  5

5

Leaf of Common Knotweed

© 2021 Adrian Briggs

 

Leaves:

Leaf Shape:

Leaf Shape is Oval

Oval

Leaf Margins:

Leaf Margin is crinkly-edged

crinkly-edged

Stem of Common Knotweed

© 2021 Adrian Briggs

 

Stem and Roots:

Stem shape:

Stem Shape is Round

Round

Root type:

Root Type is Tap

Tap